809809978 has 16 divisors (see below), whose sum is σ = 1258195680. Its totient is φ = 390446896.

The previous prime is 809809939. The next prime is 809809981. The reversal of 809809978 is 879908908.

It is a Harshad number since it is a multiple of its sum of digits (58).

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, 39525 + ... + 56407.

It is an arithmetic number, because the mean of its divisors is an integer number (78637230).

Almost surely, 2^809809978 is an apocalyptic number.

809809978 is a deficient number, since it is larger than the sum of its proper divisors (448385702).

809809978 is a wasteful number, since it uses less digits than its factorization.

809809978 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 17741.

The product of its (nonzero) digits is 2612736, while the sum is 58.

The square root of 809809978 is about 28457.1603994496. The cubic root of 809809978 is about 932.0968519451.

The spelling of 809809978 in words is "eight hundred nine million, eight hundred nine thousand, nine hundred seventy-eight".