64115810521 has 27 divisors (see below), whose sum is σ = 75954510333. Its totient is φ = 53964328320.

The previous prime is 64115810501. The next prime is 64115810569. The reversal of 64115810521 is 12501851146.

The square root of 64115810521 is 253211.

It is a perfect power (a square), and thus also a powerful number.

It can be written as a sum of positive squares in 4 ways, for example, as 14102750025 + 50013060496 = 118755^2 + 223636^2 .

It is not a de Polignac number, because 64115810521 - 2⁹ = 64115810009 is a prime.

It is a super-2 number, since 2×64115810521² (a number of 22 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (64115810501) by changing a digit.

It is a polite number, since it can be written in 26 ways as a sum of consecutive naturals, for example, 108120801 + ... + 108121393.

Almost surely, 2^64115810521 is an apocalyptic number.

64115810521 is a gapful number since it is divisible by the number (61) formed by its first and last digit.

64115810521 is the 253211-st square number.

64115810521 is the 126606-th centered octagonal number.

It is an amenable number.

64115810521 is a deficient number, since it is larger than the sum of its proper divisors (11838699812).

64115810521 is an frugal number, since it uses more digits than its factorization.

64115810521 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1322 (or 661 counting only the distinct ones).

The product of its (nonzero) digits is 9600, while the sum is 34.

The spelling of 64115810521 in words is "sixty-four billion, one hundred fifteen million, eight hundred ten thousand, five hundred twenty-one".