72191581 has 16 divisors (see below), whose sum is σ = 90223488. Its totient is φ = 56116800.

The previous prime is 72191579. The next prime is 72191597. The reversal of 72191581 is 18519127.

It is a happy number.

It is a cyclic number.

It is not a de Polignac number, because 72191581 - 2¹ = 72191579 is a prime.

It is a super-2 number, since 2×72191581² = 10423248734559122, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (72191521) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 40791 + ... + 42523.

It is an arithmetic number, because the mean of its divisors is an integer number (5638968).

Almost surely, 2^72191581 is an apocalyptic number.

It is an amenable number.

72191581 is a deficient number, since it is larger than the sum of its proper divisors (18031907).

72191581 is a wasteful number, since it uses less digits than its factorization.

72191581 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2292.

The product of its digits is 5040, while the sum is 34.

The square root of 72191581 is about 8496.5628933116. The cubic root of 72191581 is about 416.3854235060.

The spelling of 72191581 in words is "seventy-two million, one hundred ninety-one thousand, five hundred eighty-one".