72191621 has 4 divisors (see below), whose sum is σ = 75991200. Its totient is φ = 68392044.

The previous prime is 72191597. The next prime is 72191627. The reversal of 72191621 is 12619127.

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 a de Polignac number, because none of the positive numbers 2^k-72191621 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (72191627) 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, 1899761 + ... + 1899798.

It is an arithmetic number, because the mean of its divisors is an integer number (18997800).

Almost surely, 2^72191621 is an apocalyptic number.

It is an amenable number.

72191621 is a deficient number, since it is larger than the sum of its proper divisors (3799579).

72191621 is a wasteful number, since it uses less digits than its factorization.

72191621 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3799578.

The product of its digits is 1512, while the sum is 29.

The square root of 72191621 is about 8496.5652472043. The cubic root of 72191621 is about 416.3855004097.

The spelling of 72191621 in words is "seventy-two million, one hundred ninety-one thousand, six hundred twenty-one".