156557981 has 4 divisors (see below), whose sum is σ = 165767292. Its totient is φ = 147348672.

The previous prime is 156557963. The next prime is 156557993. The reversal of 156557981 is 189755651.

156557981 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 129163225 + 27394756 = 11365^2 + 5234^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-156557981 is a prime.

It is a super-2 number, since 2×156557981² = 49020802829592722, which contains 22 as substring.

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 (156557881) 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, 4604630 + ... + 4604663.

It is an arithmetic number, because the mean of its divisors is an integer number (41441823).

Almost surely, 2^156557981 is an apocalyptic number.

It is an amenable number.

156557981 is a deficient number, since it is larger than the sum of its proper divisors (9209311).

156557981 is an equidigital number, since it uses as much as digits as its factorization.

156557981 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9209310.

The product of its digits is 378000, while the sum is 47.

The square root of 156557981 is about 12512.3131754284. The cubic root of 156557981 is about 538.9623202273.

The spelling of 156557981 in words is "one hundred fifty-six million, five hundred fifty-seven thousand, nine hundred eighty-one".