78118921 has 4 divisors (see below), whose sum is σ = 78160000. Its totient is φ = 78077844.

The previous prime is 78118919. The next prime is 78118967. The reversal of 78118921 is 12981187.

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 78118921 - 2¹ = 78118919 is a prime.

It is a super-2 number, since 2×78118921² = 12205131636408482, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (78118991) 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, 17541 + ... + 21538.

It is an arithmetic number, because the mean of its divisors is an integer number (19540000).

Almost surely, 2^78118921 is an apocalyptic number.

It is an amenable number.

78118921 is a deficient number, since it is larger than the sum of its proper divisors (41079).

78118921 is a wasteful number, since it uses less digits than its factorization.

78118921 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 41078.

The product of its digits is 8064, while the sum is 37.

The square root of 78118921 is about 8838.4908779723. The cubic root of 78118921 is about 427.4828984415.

The spelling of 78118921 in words is "seventy-eight million, one hundred eighteen thousand, nine hundred twenty-one".