156207221 has 4 divisors (see below), whose sum is σ = 156234444. Its totient is φ = 156180000.

The previous prime is 156207211. The next prime is 156207223. The reversal of 156207221 is 122702651.

156207221 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

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 90516196 + 65691025 = 9514^2 + 8105^2 .

It is a cyclic number.

It is not a de Polignac number, because 156207221 - 2¹⁸ = 155945077 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 (156207223) 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, 1280 + ... + 17721.

It is an arithmetic number, because the mean of its divisors is an integer number (39058611).

Almost surely, 2^156207221 is an apocalyptic number.

It is an amenable number.

156207221 is a deficient number, since it is larger than the sum of its proper divisors (27223).

156207221 is an equidigital number, since it uses as much as digits as its factorization.

156207221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 27222.

The product of its (nonzero) digits is 1680, while the sum is 26.

The square root of 156207221 is about 12498.2887228612. The cubic root of 156207221 is about 538.5595135885.

Adding to 156207221 its reverse (122702651), we get a palindrome (278909872).

The spelling of 156207221 in words is "one hundred fifty-six million, two hundred seven thousand, two hundred twenty-one".