72138591 has 12 divisors (see below), whose sum is σ = 119086032. Its totient is φ = 41222016.

The previous prime is 72138571. The next prime is 72138593. The reversal of 72138591 is 19583127.

It is not a de Polignac number, because 72138591 - 2¹⁸ = 71876447 is a prime.

It is a super-2 number, since 2×72138591² = 10407952622930562, which contains 22 as substring.

It is a Smith number, since the sum of its digits (36) coincides with the sum of the digits of its prime factors.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (72138593) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 572466 + ... + 572591.

It is an arithmetic number, because the mean of its divisors is an integer number (9923836).

Almost surely, 2^72138591 is an apocalyptic number.

72138591 is a deficient number, since it is larger than the sum of its proper divisors (46947441).

72138591 is a wasteful number, since it uses less digits than its factorization.

72138591 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1145070 (or 1145067 counting only the distinct ones).

The product of its digits is 15120, while the sum is 36.

The square root of 72138591 is about 8493.4440011105. Note that the first 3 decimals coincide. The cubic root of 72138591 is about 416.2835202830.

The spelling of 72138591 in words is "seventy-two million, one hundred thirty-eight thousand, five hundred ninety-one".