78379921 has 4 divisors (see below), whose sum is σ = 82505200. Its totient is φ = 74254644.

The previous prime is 78379919. The next prime is 78379933. The reversal of 78379921 is 12997387.

It is a happy number.

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.

It is a cyclic number.

It is not a de Polignac number, because 78379921 - 2¹ = 78379919 is a prime.

It is a super-2 number, since 2×78379921² = 12286824031932482, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (78379901) 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, 2062611 + ... + 2062648.

It is an arithmetic number, because the mean of its divisors is an integer number (20626300).

Almost surely, 2^78379921 is an apocalyptic number.

It is an amenable number.

78379921 is a deficient number, since it is larger than the sum of its proper divisors (4125279).

78379921 is a wasteful number, since it uses less digits than its factorization.

78379921 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4125278.

The product of its digits is 190512, while the sum is 46.

The square root of 78379921 is about 8853.2435299160. The cubic root of 78379921 is about 427.9584512175.

The spelling of 78379921 in words is "seventy-eight million, three hundred seventy-nine thousand, nine hundred twenty-one".