78121679 has 4 divisors (see below), whose sum is σ = 80815560. Its totient is φ = 75427800.

The previous prime is 78121657. The next prime is 78121697. The reversal of 78121679 is 97612187.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 78121679 - 2⁸ = 78121423 is a prime.

It is a super-2 number, since 2×78121679² = 12205993459558082, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (78121609) 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, 1346897 + ... + 1346954.

It is an arithmetic number, because the mean of its divisors is an integer number (20203890).

Almost surely, 2^78121679 is an apocalyptic number.

78121679 is a deficient number, since it is larger than the sum of its proper divisors (2693881).

78121679 is a wasteful number, since it uses less digits than its factorization.

78121679 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2693880.

The product of its digits is 42336, while the sum is 41.

The square root of 78121679 is about 8838.6468987057. The cubic root of 78121679 is about 427.4879291645.

The spelling of 78121679 in words is "seventy-eight million, one hundred twenty-one thousand, six hundred seventy-nine".