156011981 has 4 divisors (see below), whose sum is σ = 157392732. Its totient is φ = 154631232.

The previous prime is 156011971. The next prime is 156011993. The reversal of 156011981 is 189110651.

156011981 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 3118756 + 152893225 = 1766^2 + 12365^2 .

It is a cyclic number.

It is not a de Polignac number, because 156011981 - 2¹⁸ = 155749837 is a prime.

It is a super-2 number, since 2×156011981² = 48679476431088722, 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 (156011971) 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, 690206 + ... + 690431.

It is an arithmetic number, because the mean of its divisors is an integer number (39348183).

Almost surely, 2^156011981 is an apocalyptic number.

It is an amenable number.

156011981 is a deficient number, since it is larger than the sum of its proper divisors (1380751).

156011981 is a wasteful number, since it uses less digits than its factorization.

156011981 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1380750.

The product of its (nonzero) digits is 2160, while the sum is 32.

The square root of 156011981 is about 12490.4756114409. The cubic root of 156011981 is about 538.3350421103.

The spelling of 156011981 in words is "one hundred fifty-six million, eleven thousand, nine hundred eighty-one".