73991321 has 4 divisors (see below), whose sum is σ = 74928000. Its totient is φ = 73054644.

The previous prime is 73991303. The next prime is 73991329. The reversal of 73991321 is 12319937.

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: 12319937 = 7 ⋅1759991.

It is a cyclic number.

It is not a de Polignac number, because 73991321 - 2²⁶ = 6882457 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (73991329) 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, 468221 + ... + 468378.

It is an arithmetic number, because the mean of its divisors is an integer number (18732000).

Almost surely, 2^73991321 is an apocalyptic number.

It is an amenable number.

73991321 is a deficient number, since it is larger than the sum of its proper divisors (936679).

73991321 is an equidigital number, since it uses as much as digits as its factorization.

73991321 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 936678.

The product of its digits is 10206, while the sum is 35.

The square root of 73991321 is about 8601.8207956223. The cubic root of 73991321 is about 419.8172315130.

The spelling of 73991321 in words is "seventy-three million, nine hundred ninety-one thousand, three hundred twenty-one".