3951503889921 has 135 divisors (see below), whose sum is σ = 6946954812369. Its totient is φ = 2231882018352.

The previous prime is 3951503889847. The next prime is 3951503889923. The reversal of 3951503889921 is 1299883051593.

The square root of 3951503889921 is 1987839.

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

3951503889921 is a `hidden beast` number, since 3 + 9 + 515 + 0 + 3 + 8 + 8 + 99 + 21 = 666.

It is not a de Polignac number, because 3951503889921 - 2⁷ = 3951503889793 is a prime.

It is a super-2 number, since 2×3951503889921² (a number of 26 digits) contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (63).

It is not an unprimeable number, because it can be changed into a prime (3951503889923) by changing a digit.

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, 17407506010 + ... + 17407506236.

Almost surely, 2^{3951503889921} is an apocalyptic number.

3951503889921 is the 1987839-th square number.

3951503889921 is the 993920-th centered octagonal number.

It is an amenable number.

3951503889921 is a deficient number, since it is larger than the sum of its proper divisors (2995450922448).

3951503889921 is an frugal number, since it uses more digits than its factorization.

3951503889921 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 758 (or 376 counting only the distinct ones).

The product of its (nonzero) digits is 20995200, while the sum is 63.

The spelling of 3951503889921 in words is "three trillion, nine hundred fifty-one billion, five hundred three million, eight hundred eighty-nine thousand, nine hundred twenty-one".