72221591 has 4 divisors (see below), whose sum is σ = 77777112. Its totient is φ = 66666072.

The previous prime is 72221561. The next prime is 72221647. The reversal of 72221591 is 19512227.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 19512227 = 7 ⋅2787461.

It is a cyclic number.

It is not a de Polignac number, because 72221591 - 2¹⁰ = 72220567 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (72221531) 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, 2777741 + ... + 2777766.

It is an arithmetic number, because the mean of its divisors is an integer number (19444278).

Almost surely, 2^72221591 is an apocalyptic number.

72221591 is a deficient number, since it is larger than the sum of its proper divisors (5555521).

72221591 is a wasteful number, since it uses less digits than its factorization.

72221591 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5555520.

The product of its digits is 2520, while the sum is 29.

The square root of 72221591 is about 8498.3287180480. The cubic root of 72221591 is about 416.4431125758.

The spelling of 72221591 in words is "seventy-two million, two hundred twenty-one thousand, five hundred ninety-one".