78408891 has 20 divisors (see below), whose sum is σ = 127778904. Its totient is φ = 47520000.

The previous prime is 78408887. The next prime is 78408899. The reversal of 78408891 is 19880487.

It is not a de Polignac number, because 78408891 - 2² = 78408887 is a prime.

It is a super-2 number, since 2×78408891² = 12295908375699762, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (78408899) by changing a digit.

It is a polite number, since it can be written in 19 ways as a sum of consecutive naturals, for example, 43110 + ... + 44891.

Almost surely, 2^78408891 is an apocalyptic number.

78408891 is a deficient number, since it is larger than the sum of its proper divisors (49370013).

78408891 is a wasteful number, since it uses less digits than its factorization.

78408891 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 88024 (or 88015 counting only the distinct ones).

The product of its (nonzero) digits is 129024, while the sum is 45.

The square root of 78408891 is about 8854.8795022857. The cubic root of 78408891 is about 428.0111706259.

The spelling of 78408891 in words is "seventy-eight million, four hundred eight thousand, eight hundred ninety-one".