77921985 has 32 divisors (see below), whose sum is σ = 129646080. Its totient is φ = 39916800.

The previous prime is 77921981. The next prime is 77921989. The reversal of 77921985 is 58912977.

It is an interprime number because it is at equal distance from previous prime (77921981) and next prime (77921989).

It is not a de Polignac number, because 77921985 - 2² = 77921981 is a prime.

It is not an unprimeable number, because it can be changed into a prime (77921981) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 117555 + ... + 118215.

It is an arithmetic number, because the mean of its divisors is an integer number (4051440).

Almost surely, 2^77921985 is an apocalyptic number.

It is an amenable number.

77921985 is a deficient number, since it is larger than the sum of its proper divisors (51724095).

77921985 is a wasteful number, since it uses less digits than its factorization.

77921985 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 969.

The product of its digits is 317520, while the sum is 48.

The square root of 77921985 is about 8827.3430317395. The cubic root of 77921985 is about 427.1233713062.

The spelling of 77921985 in words is "seventy-seven million, nine hundred twenty-one thousand, nine hundred eighty-five".