77990640 has 160 divisors (see below), whose sum is σ = 297647616. Its totient is φ = 16450560.

The previous prime is 77990639. The next prime is 77990641. The reversal of 77990640 is 4609977.

It is an interprime number because it is at equal distance from previous prime (77990639) and next prime (77990641).

It is a Harshad number since it is a multiple of its sum of digits (42).

It is a junction number, because it is equal to n+sod(n) for n = 77990592 and 77990601.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (77990641) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 20055 + ... + 23625.

Almost surely, 2^77990640 is an apocalyptic number.

77990640 is a gapful number since it is divisible by the number (70) 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 77990640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (148823808).

77990640 is an abundant number, since it is smaller than the sum of its proper divisors (219656976).

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

77990640 is a wasteful number, since it uses less digits than its factorization.

77990640 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3607 (or 3601 counting only the distinct ones).

The product of its (nonzero) digits is 95256, while the sum is 42.

The square root of 77990640 is about 8831.2309447777. The cubic root of 77990640 is about 427.2487768514.

It can be divided in two parts, 779 and 90640, that added together give a palindrome (91419).

The spelling of 77990640 in words is "seventy-seven million, nine hundred ninety thousand, six hundred forty".