77988990 has 16 divisors (see below), whose sum is σ = 187173648. Its totient is φ = 20797056.

The previous prime is 77988961. The next prime is 77988991. The reversal of 77988990 is 9988977.

It is a happy number.

It is a super-2 number, since 2×77988990² = 12164565122440200, which contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 77988990.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (77988991) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1299787 + ... + 1299846.

It is an arithmetic number, because the mean of its divisors is an integer number (11698353).

Almost surely, 2^77988990 is an apocalyptic number.

77988990 is an abundant number, since it is smaller than the sum of its proper divisors (109184658).

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

77988990 is a wasteful number, since it uses less digits than its factorization.

77988990 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2599643.

The product of its (nonzero) digits is 2286144, while the sum is 57.

The square root of 77988990 is about 8831.1375258230. The cubic root of 77988990 is about 427.2457638170.

The spelling of 77988990 in words is "seventy-seven million, nine hundred eighty-eight thousand, nine hundred ninety".