72947021 has 4 divisors (see below), whose sum is σ = 83368032. Its totient is φ = 62526012.

The previous prime is 72947011. The next prime is 72947041. The reversal of 72947021 is 12074927.

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: 12074927 = 2239 ⋅5393.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-72947021 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (72947011) 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, 5210495 + ... + 5210508.

It is an arithmetic number, because the mean of its divisors is an integer number (20842008).

Almost surely, 2^72947021 is an apocalyptic number.

It is an amenable number.

72947021 is a deficient number, since it is larger than the sum of its proper divisors (10421011).

72947021 is a wasteful number, since it uses less digits than its factorization.

72947021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10421010.

The product of its (nonzero) digits is 7056, while the sum is 32.

The square root of 72947021 is about 8540.9028211308. The cubic root of 72947021 is about 417.8327914205.

The spelling of 72947021 in words is "seventy-two million, nine hundred forty-seven thousand, twenty-one".