808978661 has 4 divisors (see below), whose sum is σ = 812606592. Its totient is φ = 805350732.

The previous prime is 808978657. The next prime is 808978669. The reversal of 808978661 is 166879808.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 808978661 - 2² = 808978657 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (808978669) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1813631 + ... + 1814076.

It is an arithmetic number, because the mean of its divisors is an integer number (203151648).

Almost surely, 2^808978661 is an apocalyptic number.

It is an amenable number.

808978661 is a deficient number, since it is larger than the sum of its proper divisors (3627931).

808978661 is a wasteful number, since it uses less digits than its factorization.

808978661 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3627930.

The product of its (nonzero) digits is 1161216, while the sum is 53.

The square root of 808978661 is about 28442.5501845387. The cubic root of 808978661 is about 931.7777922150. Note that the first 4 decimals are identical.

The spelling of 808978661 in words is "eight hundred eight million, nine hundred seventy-eight thousand, six hundred sixty-one".