2157209979 has 16 divisors (see below), whose sum is σ = 3025900800. Its totient is φ = 1365010976.

The previous prime is 2157209959. The next prime is 2157209981. The reversal of 2157209979 is 9799027512.

It is not a de Polignac number, because 2157209979 - 2⁷ = 2157209851 is a prime.

It is not an unprimeable number, because it can be changed into a prime (2157209959) 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, 204999 + ... + 215264.

It is an arithmetic number, because the mean of its divisors is an integer number (189118800).

Almost surely, 2^2157209979 is an apocalyptic number.

2157209979 is a gapful number since it is divisible by the number (29) formed by its first and last digit.

2157209979 is a deficient number, since it is larger than the sum of its proper divisors (868690821).

2157209979 is a wasteful number, since it uses less digits than its factorization.

2157209979 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 420354.

The product of its (nonzero) digits is 714420, while the sum is 51.

The square root of 2157209979 is about 46445.7746086767. The cubic root of 2157209979 is about 1292.1040077283.

The spelling of 2157209979 in words is "two billion, one hundred fifty-seven million, two hundred nine thousand, nine hundred seventy-nine".