72170731 has 2 divisors, whose sum is σ = 72170732. Its totient is φ = 72170730.

The previous prime is 72170699. The next prime is 72170737. The reversal of 72170731 is 13707127.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 72170731 - 2⁵ = 72170699 is a prime.

It is a super-2 number, since 2×72170731² = 10417228826148722, which contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 72170731.

It is not a weakly prime, because it can be changed into another prime (72170737) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 36085365 + 36085366.

It is an arithmetic number, because the mean of its divisors is an integer number (36085366).

Almost surely, 2^72170731 is an apocalyptic number.

72170731 is a deficient number, since it is larger than the sum of its proper divisors (1).

72170731 is an equidigital number, since it uses as much as digits as its factorization.

72170731 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 2058, while the sum is 28.

The square root of 72170731 is about 8495.3358379760. The cubic root of 72170731 is about 416.3453335495.

Adding to 72170731 its reverse (13707127), we get a palindrome (85877858).

The spelling of 72170731 in words is "seventy-two million, one hundred seventy thousand, seven hundred thirty-one".