991420020 has 96 divisors (see below), whose sum is σ = 3091334400. Its totient is φ = 263786112.

The previous prime is 991419973. The next prime is 991420043. The reversal of 991420020 is 20024199.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 273057 + ... + 276663.

It is an arithmetic number, because the mean of its divisors is an integer number (32201400).

Almost surely, 2^991420020 is an apocalyptic number.

991420020 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 991420020, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1545667200).

991420020 is an abundant number, since it is smaller than the sum of its proper divisors (2099914380).

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

991420020 is a wasteful number, since it uses less digits than its factorization.

991420020 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4134 (or 4126 counting only the distinct ones).

The product of its (nonzero) digits is 1296, while the sum is 27.

The square root of 991420020 is about 31486.8229581836. The cubic root of 991420020 is about 997.1317878912.

The spelling of 991420020 in words is "nine hundred ninety-one million, four hundred twenty thousand, twenty".