72166621 has 4 divisors (see below), whose sum is σ = 72881244. Its totient is φ = 71452000.

The previous prime is 72166603. The next prime is 72166637. The reversal of 72166621 is 12666127.

It is a happy number.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 67815225 + 4351396 = 8235^2 + 2086^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-72166621 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 (72116621) 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, 357160 + ... + 357361.

It is an arithmetic number, because the mean of its divisors is an integer number (18220311).

Almost surely, 2^72166621 is an apocalyptic number.

It is an amenable number.

72166621 is a deficient number, since it is larger than the sum of its proper divisors (714623).

72166621 is a wasteful number, since it uses less digits than its factorization.

72166621 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 714622.

The product of its digits is 6048, while the sum is 31.

The square root of 72166621 is about 8495.0939370910. The cubic root of 72166621 is about 416.3374300140.

The spelling of 72166621 in words is "seventy-two million, one hundred sixty-six thousand, six hundred twenty-one".