99420840 has 96 divisors (see below), whose sum is σ = 324609480. Its totient is φ = 26390016.

The previous prime is 99420833. The next prime is 99420847. The reversal of 99420840 is 4802499.

It is a happy number.

It is a Cunningham number, because it is equal to 9971²-1.

It is an interprime number because it is at equal distance from previous prime (99420833) and next prime (99420847).

It can be written as a sum of positive squares in 4 ways, for example, as 81324324 + 18096516 = 9018^2 + 4254^2 .

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a plaindrome in base 13.

It is a junction number, because it is equal to n+sod(n) for n = 99420795 and 99420804.

It is not an unprimeable number, because it can be changed into a prime (99420847) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 99222 + ... + 100218.

Almost surely, 2^99420840 is an apocalyptic number.

99420840 is a gapful number since it is divisible by the number (90) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 99420840, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (162304740).

99420840 is an abundant number, since it is smaller than the sum of its proper divisors (225188640).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

99420840 is a wasteful number, since it uses less digits than its factorization.

99420840 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1291 (or 1284 counting only the distinct ones).

The product of its (nonzero) digits is 20736, while the sum is 36.

The square root of 99420840 is about 9970.9999498546. Note that the first 4 decimals coincide. The cubic root of 99420840 is about 463.2610736762.

The spelling of 99420840 in words is "ninety-nine million, four hundred twenty thousand, eight hundred forty".