2157121138879 has 16 divisors (see below), whose sum is σ = 2475842241600. Its totient is φ = 1841048031744.

The previous prime is 2157121138859. The next prime is 2157121138897. The reversal of 2157121138879 is 9788311217512.

It is a cyclic number.

It is not a de Polignac number, because 2157121138879 - 2¹⁷ = 2157121007807 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (2157121138829) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 3023757 + ... + 3668425.

It is an arithmetic number, because the mean of its divisors is an integer number (154740140100).

Almost surely, 2^{2157121138879} is an apocalyptic number.

2157121138879 is a deficient number, since it is larger than the sum of its proper divisors (318721102721).

2157121138879 is a wasteful number, since it uses less digits than its factorization.

2157121138879 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 646722.

The product of its digits is 1693440, while the sum is 55.

The spelling of 2157121138879 in words is "two trillion, one hundred fifty-seven billion, one hundred twenty-one million, one hundred thirty-eight thousand, eight hundred seventy-nine".