2156221531 has 2 divisors, whose sum is σ = 2156221532. Its totient is φ = 2156221530.

The previous prime is 2156221499. The next prime is 2156221547. The reversal of 2156221531 is 1351226512.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 2156221531 - 2⁵ = 2156221499 is a prime.

It is a super-2 number, since 2×2156221531² = 9298582581495967922, which contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 2156221531.

It is not a weakly prime, because it can be changed into another prime (2156221031) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1078110765 + 1078110766.

It is an arithmetic number, because the mean of its divisors is an integer number (1078110766).

Almost surely, 2^2156221531 is an apocalyptic number.

2156221531 is a deficient number, since it is larger than the sum of its proper divisors (1).

2156221531 is an equidigital number, since it uses as much as digits as its factorization.

2156221531 is an evil number, because the sum of its binary digits is even.

The product of its digits is 3600, while the sum is 28.

The square root of 2156221531 is about 46435.1325076175. The cubic root of 2156221531 is about 1291.9066273536.

The spelling of 2156221531 in words is "two billion, one hundred fifty-six million, two hundred twenty-one thousand, five hundred thirty-one".