72721507 has 4 divisors (see below), whose sum is σ = 72800056. Its totient is φ = 72642960.

The previous prime is 72721487. The next prime is 72721511. The reversal of 72721507 is 70512727.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 70512727 = 71 ⋅993137.

It is a cyclic number.

It is not a de Polignac number, because 72721507 - 2¹⁵ = 72688739 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (72721547) 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, 37869 + ... + 39742.

It is an arithmetic number, because the mean of its divisors is an integer number (18200014).

Almost surely, 2^72721507 is an apocalyptic number.

72721507 is a deficient number, since it is larger than the sum of its proper divisors (78549).

72721507 is an equidigital number, since it uses as much as digits as its factorization.

72721507 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 78548.

The product of its (nonzero) digits is 6860, while the sum is 31.

The square root of 72721507 is about 8527.6906017984. The cubic root of 72721507 is about 417.4017735380.

The spelling of 72721507 in words is "seventy-two million, seven hundred twenty-one thousand, five hundred seven".