78990251 has 4 divisors (see below), whose sum is σ = 79012032. Its totient is φ = 78968472.

The previous prime is 78990199. The next prime is 78990271. The reversal of 78990251 is 15209987.

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 78990251 - 2¹⁰ = 78989227 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 78990199 and 78990208.

It is not an unprimeable number, because it can be changed into a prime (78990271) 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, 3995 + ... + 13188.

It is an arithmetic number, because the mean of its divisors is an integer number (19753008).

Almost surely, 2^78990251 is an apocalyptic number.

78990251 is a deficient number, since it is larger than the sum of its proper divisors (21781).

78990251 is a wasteful number, since it uses less digits than its factorization.

78990251 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 21780.

The product of its (nonzero) digits is 45360, while the sum is 41.

The square root of 78990251 is about 8887.6459762977. The cubic root of 78990251 is about 429.0663915954.

The spelling of 78990251 in words is "seventy-eight million, nine hundred ninety thousand, two hundred fifty-one".