72915421 has 4 divisors (see below), whose sum is σ = 72984700. Its totient is φ = 72846144.

The previous prime is 72915347. The next prime is 72915433. The reversal of 72915421 is 12451927.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 12451927 = 2957 ⋅4211.

It can be written as a sum of positive squares in 2 ways, for example, as 34351321 + 38564100 = 5861^2 + 6210^2 .

It is a cyclic number.

It is not a de Polignac number, because 72915421 - 2¹⁹ = 72391133 is a prime.

It is a Duffinian number.

It is a plaindrome in base 16.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (72915461) 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, 33036 + ... + 35173.

It is an arithmetic number, because the mean of its divisors is an integer number (18246175).

Almost surely, 2^72915421 is an apocalyptic number.

It is an amenable number.

72915421 is a deficient number, since it is larger than the sum of its proper divisors (69279).

72915421 is a wasteful number, since it uses less digits than its factorization.

72915421 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 69278.

The product of its digits is 5040, while the sum is 31.

The square root of 72915421 is about 8539.0526992167. The cubic root of 72915421 is about 417.7724488914.

The spelling of 72915421 in words is "seventy-two million, nine hundred fifteen thousand, four hundred twenty-one".