72170621 has 2 divisors, whose sum is σ = 72170622. Its totient is φ = 72170620.

The previous prime is 72170599. The next prime is 72170663. The reversal of 72170621 is 12607127.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 62647225 + 9523396 = 7915^2 + 3086^2 .

It is a cyclic number.

It is not a de Polignac number, because 72170621 - 2⁶ = 72170557 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (72170221) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 36085310 + 36085311.

It is an arithmetic number, because the mean of its divisors is an integer number (36085311).

Almost surely, 2^72170621 is an apocalyptic number.

It is an amenable number.

72170621 is a deficient number, since it is larger than the sum of its proper divisors (1).

72170621 is an equidigital number, since it uses as much as digits as its factorization.

72170621 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 1176, while the sum is 26.

The square root of 72170621 is about 8495.3293638328. The cubic root of 72170621 is about 416.3451220233.

Adding to 72170621 its reverse (12607127), we get a palindrome (84777748).

The spelling of 72170621 in words is "seventy-two million, one hundred seventy thousand, six hundred twenty-one".