86640921 has 28 divisors (see below), whose sum is σ = 130902052. Its totient is φ = 57316896.

The previous prime is 86640919. The next prime is 86640943. The reversal of 86640921 is 12904668.

86640921 is a `hidden beast` number, since 8 + 6 + 640 + 9 + 2 + 1 = 666.

It can be written as a sum of positive squares in 2 ways, for example, as 39237696 + 47403225 = 6264^2 + 6885^2 .

It is not a de Polignac number, because 86640921 - 2¹ = 86640919 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (86640121) by changing a digit.

It is a polite number, since it can be written in 27 ways as a sum of consecutive naturals, for example, 114075 + ... + 114831.

Almost surely, 2^86640921 is an apocalyptic number.

86640921 is a gapful number since it is divisible by the number (81) formed by its first and last digit.

It is an amenable number.

86640921 is a deficient number, since it is larger than the sum of its proper divisors (44261131).

86640921 is an equidigital number, since it uses as much as digits as its factorization.

86640921 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 932 (or 917 counting only the distinct ones).

The product of its (nonzero) digits is 20736, while the sum is 36.

The square root of 86640921 is about 9308.1104956914. The cubic root of 86640921 is about 442.4943061606.

It can be divided in two parts, 8 and 6640921, that added together give a square (6640929 = 2577²).

The spelling of 86640921 in words is "eighty-six million, six hundred forty thousand, nine hundred twenty-one".