64531881 has 24 divisors (see below), whose sum is σ = 99243144. Its totient is φ = 40266240.

The previous prime is 64531879. The next prime is 64531891. The reversal of 64531881 is 18813546.

64531881 is a `hidden beast` number, since 645 + 3 + 1 + 8 + 8 + 1 = 666.

It can be written as a sum of positive squares in 4 ways, for example, as 53582400 + 10949481 = 7320^2 + 3309^2 .

It is not a de Polignac number, because 64531881 - 2¹ = 64531879 is a prime.

It is a super-2 number, since 2×64531881² = 8328727330796322, which contains 22 as substring.

It is a hoax number, since the sum of its digits (36) coincides with the sum of the digits of its distinct prime factors.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (64531871) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 29071 + ... + 31211.

It is an arithmetic number, because the mean of its divisors is an integer number (4135131).

Almost surely, 2^64531881 is an apocalyptic number.

It is an amenable number.

64531881 is a deficient number, since it is larger than the sum of its proper divisors (34711263).

64531881 is a wasteful number, since it uses less digits than its factorization.

64531881 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2361 (or 2358 counting only the distinct ones).

The product of its digits is 23040, while the sum is 36.

The square root of 64531881 is about 8033.1737812648. The cubic root of 64531881 is about 401.1050298780.

The spelling of 64531881 in words is "sixty-four million, five hundred thirty-one thousand, eight hundred eighty-one".