2157221499 has 4 divisors (see below), whose sum is σ = 2876295336. Its totient is φ = 1438147664.

The previous prime is 2157221489. The next prime is 2157221501. The reversal of 2157221499 is 9941227512.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 2157221499 - 2⁴ = 2157221483 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 2157221499.

It is not an unprimeable number, because it can be changed into a prime (2157221489) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 359536914 + ... + 359536919.

It is an arithmetic number, because the mean of its divisors is an integer number (719073834).

Almost surely, 2^2157221499 is an apocalyptic number.

2157221499 is a deficient number, since it is larger than the sum of its proper divisors (719073837).

2157221499 is an equidigital number, since it uses as much as digits as its factorization.

2157221499 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 719073836.

The product of its digits is 90720, while the sum is 42.

The square root of 2157221499 is about 46445.8986240981. The cubic root of 2157221499 is about 1292.1063077689.

It can be divided in two parts, 21572 and 21499, that added together give a triangular number (43071 = T₂₉₃).

The spelling of 2157221499 in words is "two billion, one hundred fifty-seven million, two hundred twenty-one thousand, four hundred ninety-nine".