78978990 has 16 divisors (see below), whose sum is σ = 189549648. Its totient is φ = 21061056.

The previous prime is 78978971. The next prime is 78979001. The reversal of 78978990 is 9987987.

It is a happy number.

It is a super-2 number, since 2×78978990² = 12475361722840200, which contains 22 as substring.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 78978990.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1316287 + ... + 1316346.

It is an arithmetic number, because the mean of its divisors is an integer number (11846853).

Almost surely, 2^78978990 is an apocalyptic number.

78978990 is an abundant number, since it is smaller than the sum of its proper divisors (110570658).

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

78978990 is a wasteful number, since it uses less digits than its factorization.

78978990 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2632643.

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

The square root of 78978990 is about 8887.0124338835. The cubic root of 78978990 is about 429.0460011202.

The spelling of 78978990 in words is "seventy-eight million, nine hundred seventy-eight thousand, nine hundred ninety".