78922021 has 4 divisors (see below), whose sum is σ = 81643500. Its totient is φ = 76200544.

The previous prime is 78921989. The next prime is 78922031. The reversal of 78922021 is 12022987.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 12022987 = 829 ⋅14503.

It can be written as a sum of positive squares in 2 ways, for example, as 12320100 + 66601921 = 3510^2 + 8161^2 .

It is a cyclic number.

It is not a de Polignac number, because 78922021 - 2⁵ = 78921989 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (78922031) 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, 1360696 + ... + 1360753.

It is an arithmetic number, because the mean of its divisors is an integer number (20410875).

Almost surely, 2^78922021 is an apocalyptic number.

It is an amenable number.

78922021 is a deficient number, since it is larger than the sum of its proper divisors (2721479).

78922021 is a wasteful number, since it uses less digits than its factorization.

78922021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2721478.

The product of its (nonzero) digits is 4032, while the sum is 31.

The square root of 78922021 is about 8883.8066728177. The cubic root of 78922021 is about 428.9428167126.

The spelling of 78922021 in words is "seventy-eight million, nine hundred twenty-two thousand, twenty-one".