64136725621 has 8 divisors (see below), whose sum is σ = 65777736024. Its totient is φ = 62499367680.

The previous prime is 64136725619. The next prime is 64136725669. The reversal of 64136725621 is 12652763146.

It can be written as a sum of positive squares in 4 ways, for example, as 16803936900 + 47332788721 = 129630^2 + 217561^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 64136725621 - 2¹ = 64136725619 is a prime.

It is a super-2 number, since 2×64136725621² (a number of 22 digits) contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (64136725691) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 877530 + ... + 947803.

It is an arithmetic number, because the mean of its divisors is an integer number (8222217003).

Almost surely, 2^64136725621 is an apocalyptic number.

It is an amenable number.

64136725621 is a deficient number, since it is larger than the sum of its proper divisors (1641010403).

64136725621 is a wasteful number, since it uses less digits than its factorization.

64136725621 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1826231.

The product of its digits is 362880, while the sum is 43.

The spelling of 64136725621 in words is "sixty-four billion, one hundred thirty-six million, seven hundred twenty-five thousand, six hundred twenty-one".