78099121 has 4 divisors (see below), whose sum is σ = 78117412. Its totient is φ = 78080832.

The previous prime is 78099103. The next prime is 78099127. The reversal of 78099121 is 12199087.

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

It can be written as a sum of positive squares in 2 ways, for example, as 25391521 + 52707600 = 5039^2 + 7260^2 .

It is a cyclic number.

It is not a de Polignac number, because 78099121 - 2⁵ = 78099089 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (78099127) 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, 1045 + ... + 12541.

It is an arithmetic number, because the mean of its divisors is an integer number (19529353).

Almost surely, 2^78099121 is an apocalyptic number.

It is an amenable number.

78099121 is a deficient number, since it is larger than the sum of its proper divisors (18291).

78099121 is a wasteful number, since it uses less digits than its factorization.

78099121 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 18290.

The product of its (nonzero) digits is 9072, while the sum is 37.

The square root of 78099121 is about 8837.3707062678. The cubic root of 78099121 is about 427.4467788242.

The spelling of 78099121 in words is "seventy-eight million, ninety-nine thousand, one hundred twenty-one".