2157999909 has 16 divisors (see below), whose sum is σ = 3233392512. Its totient is φ = 1270260288.

The previous prime is 2157999889. The next prime is 2157999911. The reversal of 2157999909 is 9099997512.

It is not a de Polignac number, because 2157999909 - 2²¹ = 2155902757 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (2157999919) 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, 1202002 + ... + 1203795.

It is an arithmetic number, because the mean of its divisors is an integer number (202087032).

Almost surely, 2^2157999909 is an apocalyptic number.

It is an amenable number.

2157999909 is a deficient number, since it is larger than the sum of its proper divisors (1075392603).

2157999909 is a wasteful number, since it uses less digits than its factorization.

2157999909 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2405836.

The product of its (nonzero) digits is 4133430, while the sum is 60.

The square root of 2157999909 is about 46454.2776178900. The cubic root of 2157999909 is about 1292.2617032657.

The spelling of 2157999909 in words is "two billion, one hundred fifty-seven million, nine hundred ninety-nine thousand, nine hundred nine".