156120721 has 2 divisors, whose sum is σ = 156120722. Its totient is φ = 156120720.

The previous prime is 156120709. The next prime is 156120733. The reversal of 156120721 is 127021651.

It is a balanced prime because it is at equal distance from previous prime (156120709) and next prime (156120733).

It can be written as a sum of positive squares in only one way, i.e., 121440400 + 34680321 = 11020^2 + 5889^2 .

It is a cyclic number.

It is not a de Polignac number, because 156120721 - 2⁵ = 156120689 is a prime.

It is not a weakly prime, because it can be changed into another prime (156120761) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 78060360 + 78060361.

It is an arithmetic number, because the mean of its divisors is an integer number (78060361).

Almost surely, 2^156120721 is an apocalyptic number.

It is an amenable number.

156120721 is a deficient number, since it is larger than the sum of its proper divisors (1).

156120721 is an equidigital number, since it uses as much as digits as its factorization.

156120721 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 840, while the sum is 25.

The square root of 156120721 is about 12494.8277699214. The cubic root of 156120721 is about 538.4600858344.

The spelling of 156120721 in words is "one hundred fifty-six million, one hundred twenty thousand, seven hundred twenty-one".