156220561 has 4 divisors (see below), whose sum is σ = 178537792. Its totient is φ = 133903332.

The previous prime is 156220529. The next prime is 156220567. The reversal of 156220561 is 165022651.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 165022651 = 367 ⋅449653.

It is a cyclic number.

It is not a de Polignac number, because 156220561 - 2⁵ = 156220529 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (156220567) 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, 11158605 + ... + 11158618.

It is an arithmetic number, because the mean of its divisors is an integer number (44634448).

Almost surely, 2^156220561 is an apocalyptic number.

It is an amenable number.

156220561 is a deficient number, since it is larger than the sum of its proper divisors (22317231).

156220561 is an equidigital number, since it uses as much as digits as its factorization.

156220561 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 22317230.

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

The square root of 156220561 is about 12498.8223845289. The cubic root of 156220561 is about 538.5748440352.

The spelling of 156220561 in words is "one hundred fifty-six million, two hundred twenty thousand, five hundred sixty-one".