2638899531961 has 135 divisors (see below), whose sum is σ = 3634844049963. Its totient is φ = 1908816053760.

The previous prime is 2638899531929. The next prime is 2638899531967. The reversal of 2638899531961 is 1691359988362.

The square root of 2638899531961 is 1624469.

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

2638899531961 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It can be written as a sum of positive squares in 7 ways, for example, as 42109092025 + 2596790439936 = 205205^2 + 1611456^2 .

It is not a de Polignac number, because 2638899531961 - 2⁵ = 2638899531929 is a prime.

It is a Smith number, since the sum of its digits (70) coincides with the sum of the digits of its prime factors.

Its product of digits (151165440) is a multiple of the sum of its prime divisors (108).

It is not an unprimeable number, because it can be changed into a prime (2638899531967) by changing a digit.

It is a polite number, since it can be written in 134 ways as a sum of consecutive naturals, for example, 36149308621 + ... + 36149308693.

Almost surely, 2^{2638899531961} is an apocalyptic number.

2638899531961 is the 1624469-th square number.

2638899531961 is the 812235-th centered octagonal number.

It is an amenable number.

2638899531961 is a deficient number, since it is larger than the sum of its proper divisors (995944518002).

2638899531961 is an frugal number, since it uses more digits than its factorization.

2638899531961 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 250 (or 108 counting only the distinct ones).

The product of its digits is 151165440, while the sum is 70.

The spelling of 2638899531961 in words is "two trillion, six hundred thirty-eight billion, eight hundred ninety-nine million, five hundred thirty-one thousand, nine hundred sixty-one".