72978121 has 4 divisors (see below), whose sum is σ = 73386000. Its totient is φ = 72570244.

The previous prime is 72978077. The next prime is 72978133. The reversal of 72978121 is 12187927.

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: 12187927 = 89 ⋅136943.

It is a cyclic number.

It is not a de Polignac number, because 72978121 - 2⁹ = 72977609 is a prime.

It is a super-2 number, since 2×72978121² = 10651612289381282, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (72978151) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 203671 + ... + 204028.

It is an arithmetic number, because the mean of its divisors is an integer number (18346500).

Almost surely, 2^72978121 is an apocalyptic number.

It is an amenable number.

72978121 is a deficient number, since it is larger than the sum of its proper divisors (407879).

72978121 is a wasteful number, since it uses less digits than its factorization.

72978121 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 407878.

The product of its digits is 14112, while the sum is 37.

The square root of 72978121 is about 8542.7232777376. The cubic root of 72978121 is about 417.8921621500.

The spelling of 72978121 in words is "seventy-two million, nine hundred seventy-eight thousand, one hundred twenty-one".