72138977 has 4 divisors (see below), whose sum is σ = 72167616. Its totient is φ = 72110340.

The previous prime is 72138943. The next prime is 72139003. The reversal of 72138977 is 77983127.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 72138977 - 2²² = 67944673 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (72138917) 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, 10133 + ... + 15714.

It is an arithmetic number, because the mean of its divisors is an integer number (18041904).

Almost surely, 2^72138977 is an apocalyptic number.

It is an amenable number.

72138977 is a deficient number, since it is larger than the sum of its proper divisors (28639).

72138977 is a wasteful number, since it uses less digits than its factorization.

72138977 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 28638.

The product of its digits is 148176, while the sum is 44.

The square root of 72138977 is about 8493.4667244889. The cubic root of 72138977 is about 416.2842627666.

The spelling of 72138977 in words is "seventy-two million, one hundred thirty-eight thousand, nine hundred seventy-seven".