72606721 has 4 divisors (see below), whose sum is σ = 79207344. Its totient is φ = 66006100.

The previous prime is 72606719. The next prime is 72606727. The reversal of 72606721 is 12760627.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 12760627 = 11 ⋅1160057.

It is a cyclic number.

It is not a de Polignac number, because 72606721 - 2¹ = 72606719 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (72606727) 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, 3300295 + ... + 3300316.

It is an arithmetic number, because the mean of its divisors is an integer number (19801836).

Almost surely, 2^72606721 is an apocalyptic number.

It is an amenable number.

72606721 is a deficient number, since it is larger than the sum of its proper divisors (6600623).

72606721 is a wasteful number, since it uses less digits than its factorization.

72606721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6600622.

The product of its (nonzero) digits is 7056, while the sum is 31.

The square root of 72606721 is about 8520.9577513329. The cubic root of 72606721 is about 417.1820443609.

The spelling of 72606721 in words is "seventy-two million, six hundred six thousand, seven hundred twenty-one".