64720825821 has 24 divisors (see below), whose sum is σ = 98777296800. Its totient is φ = 42333110352.

The previous prime is 64720825811. The next prime is 64720825837. The reversal of 64720825821 is 12852802746.

64720825821 is a `hidden beast` number, since 6 + 47 + 20 + 8 + 2 + 582 + 1 = 666.

It is not a de Polignac number, because 64720825821 - 2⁵ = 64720825789 is a prime.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (64720825801) 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, 2499771 + ... + 2525528.

It is an arithmetic number, because the mean of its divisors is an integer number (4115720700).

Almost surely, 2^64720825821 is an apocalyptic number.

It is an amenable number.

64720825821 is a deficient number, since it is larger than the sum of its proper divisors (34056470979).

64720825821 is an equidigital number, since it uses as much as digits as its factorization.

64720825821 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5025367 (or 5025355 counting only the distinct ones).

The product of its (nonzero) digits is 430080, while the sum is 45.

The spelling of 64720825821 in words is "sixty-four billion, seven hundred twenty million, eight hundred twenty-five thousand, eight hundred twenty-one".