78313921 has 8 divisors (see below), whose sum is σ = 89625920. Its totient is φ = 67033008.

The previous prime is 78313909. The next prime is 78313927. The reversal of 78313921 is 12931387.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 78313921 - 2¹⁷ = 78182849 is a prime.

It is a super-2 number, since 2×78313921² = 12266140444788482, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (78313927) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 2091 + ... + 12688.

It is an arithmetic number, because the mean of its divisors is an integer number (11203240).

Almost surely, 2^78313921 is an apocalyptic number.

It is an amenable number.

78313921 is a deficient number, since it is larger than the sum of its proper divisors (11311999).

78313921 is a wasteful number, since it uses less digits than its factorization.

78313921 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 15543.

The product of its digits is 9072, while the sum is 34.

The square root of 78313921 is about 8849.5152974612. The cubic root of 78313921 is about 427.8382963397.

The spelling of 78313921 in words is "seventy-eight million, three hundred thirteen thousand, nine hundred twenty-one".