156342221 has 4 divisors (see below), whose sum is σ = 178676832. Its totient is φ = 134007612.

The previous prime is 156342211. The next prime is 156342259. The reversal of 156342221 is 122243651.

It is a happy number.

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: 122243651 = 17 ⋅7190803.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-156342221 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (156342211) 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, 11167295 + ... + 11167308.

It is an arithmetic number, because the mean of its divisors is an integer number (44669208).

Almost surely, 2^156342221 is an apocalyptic number.

It is an amenable number.

156342221 is a deficient number, since it is larger than the sum of its proper divisors (22334611).

156342221 is an equidigital number, since it uses as much as digits as its factorization.

156342221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 22334610.

The product of its digits is 2880, while the sum is 26.

The square root of 156342221 is about 12503.6882958589. The cubic root of 156342221 is about 538.7146165323.

Adding to 156342221 its reverse (122243651), we get a palindrome (278585872).

The spelling of 156342221 in words is "one hundred fifty-six million, three hundred forty-two thousand, two hundred twenty-one".