251978 has 12 divisors (see below), whose sum is σ = 400050. Its totient is φ = 119016.

The previous prime is 251971. The next prime is 251983. The reversal of 251978 is 879152.

251978 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It can be written as a sum of positive squares in only one way, i.e., 190969 + 61009 = 437^2 + 247^2 .

It is not an unprimeable number, because it can be changed into a prime (251971) by changing a digit.

251978 is an untouchable number, because it is not equal to the sum of proper divisors of any number.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 548 + ... + 896.

2²⁵¹⁹⁷⁸ is an apocalyptic number.

251978 is a deficient number, since it is larger than the sum of its proper divisors (148072).

251978 is a wasteful number, since it uses less digits than its factorization.

251978 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 389 (or 370 counting only the distinct ones).

The product of its digits is 5040, while the sum is 32.

The square root of 251978 is about 501.9741029177. The cubic root of 251978 is about 63.1617578290.

The spelling of 251978 in words is "two hundred fifty-one thousand, nine hundred seventy-eight".