72610721 has 2 divisors, whose sum is σ = 72610722. Its totient is φ = 72610720.

The previous prime is 72610709. The next prime is 72610729. The reversal of 72610721 is 12701627.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 72063121 + 547600 = 8489^2 + 740^2 .

It is an emirp because it is prime and its reverse (12701627) is a distict prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-72610721 is a prime.

It is equal to p_4262534 and since 72610721 and 4262534 have the same sum of digits, it is a Honaker prime.

It is not a weakly prime, because it can be changed into another prime (72610729) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 36305360 + 36305361.

It is an arithmetic number, because the mean of its divisors is an integer number (36305361).

Almost surely, 2^72610721 is an apocalyptic number.

It is an amenable number.

72610721 is a deficient number, since it is larger than the sum of its proper divisors (1).

72610721 is an equidigital number, since it uses as much as digits as its factorization.

72610721 is an evil number, because the sum of its binary digits is even.

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

The square root of 72610721 is about 8521.1924634995. The cubic root of 72610721 is about 417.1897052566.

The spelling of 72610721 in words is "seventy-two million, six hundred ten thousand, seven hundred twenty-one".