3972156491 has 4 divisors (see below), whose sum is σ = 4001150472. Its totient is φ = 3943162512.

The previous prime is 3972156421. The next prime is 3972156493. The reversal of 3972156491 is 1946512793.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-3972156491 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (3972156493) 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, 14496785 + ... + 14497058.

It is an arithmetic number, because the mean of its divisors is an integer number (1000287618).

Almost surely, 2^3972156491 is an apocalyptic number.

3972156491 is a deficient number, since it is larger than the sum of its proper divisors (28993981).

3972156491 is a wasteful number, since it uses less digits than its factorization.

3972156491 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 28993980.

The product of its digits is 408240, while the sum is 47.

The square root of 3972156491 is about 63025.0465370713. The cubic root of 3972156491 is about 1583.7092379602.

The spelling of 3972156491 in words is "three billion, nine hundred seventy-two million, one hundred fifty-six thousand, four hundred ninety-one".