251994978 has 96 divisors (see below), whose sum is σ = 607791600. Its totient is φ = 75091968.

The previous prime is 251994937. The next prime is 251994989. The reversal of 251994978 is 879499152.

It can be written as a sum of positive squares in 8 ways, for example, as 139783329 + 112211649 = 11823^2 + 10593^2 .

It is a hoax number, since the sum of its digits (54) coincides with the sum of the digits of its distinct prime factors.

It is an unprimeable number.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 647608 + ... + 647996.

Almost surely, 2^251994978 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 251994978, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (303895800).

251994978 is an abundant number, since it is smaller than the sum of its proper divisors (355796622).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

251994978 is a wasteful number, since it uses less digits than its factorization.

251994978 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 516 (or 513 counting only the distinct ones).

The product of its digits is 1632960, while the sum is 54.

The square root of 251994978 is about 15874.3496874675. The cubic root of 251994978 is about 631.6317638703.

It can be divided in two parts, 25 and 1994978, that added together give a triangular number (1995003 = T₁₉₉₇).

The spelling of 251994978 in words is "two hundred fifty-one million, nine hundred ninety-four thousand, nine hundred seventy-eight".