72171979 has 4 divisors (see below), whose sum is σ = 78733080. Its totient is φ = 65610880.

The previous prime is 72171973. The next prime is 72171989. The reversal of 72171979 is 97917127.

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

It is a cyclic number.

It is not a de Polignac number, because 72171979 - 2³ = 72171971 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (72171971) 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, 3280534 + ... + 3280555.

It is an arithmetic number, because the mean of its divisors is an integer number (19683270).

Almost surely, 2^72171979 is an apocalyptic number.

72171979 is a deficient number, since it is larger than the sum of its proper divisors (6561101).

72171979 is a wasteful number, since it uses less digits than its factorization.

72171979 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6561100.

The product of its digits is 55566, while the sum is 43.

The square root of 72171979 is about 8495.4092897282. The cubic root of 72171979 is about 416.3477333958.

The spelling of 72171979 in words is "seventy-two million, one hundred seventy-one thousand, nine hundred seventy-nine".