64731821 has 16 divisors (see below), whose sum is σ = 84215808. Its totient is φ = 48246000.

The previous prime is 64731817. The next prime is 64731839. The reversal of 64731821 is 12813746.

It is not a de Polignac number, because 64731821 - 2² = 64731817 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (64731811) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 16505 + ... + 20046.

It is an arithmetic number, because the mean of its divisors is an integer number (5263488).

Almost surely, 2^64731821 is an apocalyptic number.

It is an amenable number.

64731821 is a deficient number, since it is larger than the sum of its proper divisors (19483987).

64731821 is a wasteful number, since it uses less digits than its factorization.

64731821 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 36592.

The product of its digits is 8064, while the sum is 32.

The square root of 64731821 is about 8045.6088023219. The cubic root of 64731821 is about 401.5188525013.

The spelling of 64731821 in words is "sixty-four million, seven hundred thirty-one thousand, eight hundred twenty-one".