642121755625 has 135 divisors (see below), whose sum is σ = 989215061571. Its totient is φ = 415406880000.

The previous prime is 642121755617. The next prime is 642121755641. The reversal of 642121755625 is 526557121246.

It is a happy number.

The square root of 642121755625 is 801325.

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

It can be written as a sum of positive squares in 7 ways, for example, as 333643709161 + 308478046464 = 577619^2 + 555408^2 .

It is not a de Polignac number, because 642121755625 - 2³ = 642121755617 is a prime.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 134 ways as a sum of consecutive naturals, for example, 2664405505 + ... + 2664405745.

Almost surely, 2^642121755625 is an apocalyptic number.

642121755625 is the 801325-th square number.

642121755625 is the 400663-rd centered octagonal number.

It is an amenable number.

642121755625 is a deficient number, since it is larger than the sum of its proper divisors (347093305946).

642121755625 is an frugal number, since it uses more digits than its factorization.

642121755625 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 554 (or 272 counting only the distinct ones).

The product of its digits is 1008000, while the sum is 46.

The spelling of 642121755625 in words is "six hundred forty-two billion, one hundred twenty-one million, seven hundred fifty-five thousand, six hundred twenty-five".