2121639723 has 40 divisors (see below), whose sum is σ = 3627816192. Its totient is φ = 1210462704.

The previous prime is 2121639703. The next prime is 2121639727. The reversal of 2121639723 is 3279361212.

2121639723 is a `hidden beast` number, since 2 + 12 + 1 + 639 + 7 + 2 + 3 = 666.

It is not a de Polignac number, because 2121639723 - 2⁵ = 2121639691 is a prime.

It is a super-2 number, since 2×2121639723² = 9002710228423033458, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (2121639727) by changing a digit.

It is a polite number, since it can be written in 39 ways as a sum of consecutive naturals, for example, 409636 + ... + 414782.

Almost surely, 2^2121639723 is an apocalyptic number.

2121639723 is a deficient number, since it is larger than the sum of its proper divisors (1506176469).

2121639723 is an equidigital number, since it uses as much as digits as its factorization.

2121639723 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5893 (or 5884 counting only the distinct ones).

The product of its digits is 27216, while the sum is 36.

The square root of 2121639723 is about 46061.2605450611. The cubic root of 2121639723 is about 1284.9627736292.

The spelling of 2121639723 in words is "two billion, one hundred twenty-one million, six hundred thirty-nine thousand, seven hundred twenty-three".