72171621 has 16 divisors (see below), whose sum is σ = 107545920. Its totient is φ = 47833200.

The previous prime is 72171611. The next prime is 72171629. The reversal of 72171621 is 12617127.

It is not a de Polignac number, because 72171621 - 2⁹ = 72171109 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (72171629) 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, 3055 + ... + 12396.

It is an arithmetic number, because the mean of its divisors is an integer number (6721620).

Almost surely, 2^72171621 is an apocalyptic number.

It is an amenable number.

72171621 is a deficient number, since it is larger than the sum of its proper divisors (35374299).

72171621 is a wasteful number, since it uses less digits than its factorization.

72171621 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 15633 (or 15627 counting only the distinct ones).

The product of its digits is 1176, while the sum is 27.

The square root of 72171621 is about 8495.3882194989. The cubic root of 72171621 is about 416.3470449812.

Adding to 72171621 its reverse (12617127), we get a palindrome (84788748).

The spelling of 72171621 in words is "seventy-two million, one hundred seventy-one thousand, six hundred twenty-one".