2159756021 has 4 divisors (see below), whose sum is σ = 2169187500. Its totient is φ = 2150324544.

The previous prime is 2159756009. The next prime is 2159756059. The reversal of 2159756021 is 1206579512.

It is a happy number.

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

It can be written as a sum of positive squares in 2 ways, for example, as 1352400625 + 807355396 = 36775^2 + 28414^2 .

It is a cyclic number.

It is not a de Polignac number, because 2159756021 - 2²² = 2155561717 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (2159758021) 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, 4715396 + ... + 4715853.

It is an arithmetic number, because the mean of its divisors is an integer number (542296875).

Almost surely, 2^2159756021 is an apocalyptic number.

It is an amenable number.

2159756021 is a deficient number, since it is larger than the sum of its proper divisors (9431479).

2159756021 is an equidigital number, since it uses as much as digits as its factorization.

2159756021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9431478.

The product of its (nonzero) digits is 37800, while the sum is 38.

The square root of 2159756021 is about 46473.1752842433. The cubic root of 2159756021 is about 1292.6121421105.

The spelling of 2159756021 in words is "two billion, one hundred fifty-nine million, seven hundred fifty-six thousand, twenty-one".