156581981 has 8 divisors (see below), whose sum is σ = 161033184. Its totient is φ = 152186320.

The previous prime is 156581947. The next prime is 156581989. The reversal of 156581981 is 189185651.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a de Polignac number, because none of the positive numbers 2^k-156581981 is a prime.

It is a super-2 number, since 2×156581981² = 49035833547768722, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (156581989) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 8135 + ... + 19476.

It is an arithmetic number, because the mean of its divisors is an integer number (20129148).

Almost surely, 2^156581981 is an apocalyptic number.

It is an amenable number.

156581981 is a deficient number, since it is larger than the sum of its proper divisors (4451203).

156581981 is a wasteful number, since it uses less digits than its factorization.

156581981 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 27771.

The product of its digits is 86400, while the sum is 44.

The square root of 156581981 is about 12513.2721939547. The cubic root of 156581981 is about 538.9898594063.

The spelling of 156581981 in words is "one hundred fifty-six million, five hundred eighty-one thousand, nine hundred eighty-one".