251978688 has 140 divisors (see below), whose sum is σ = 804616120. Its totient is φ = 77511168.

The previous prime is 251978681. The next prime is 251978689. The reversal of 251978688 is 886879152.

It is a Harshad number since it is a multiple of its sum of digits (54).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (251978681) by changing a digit.

It is a polite number, since it can be written in 19 ways as a sum of consecutive naturals, for example, 65523 + ... + 69261.

It is an arithmetic number, because the mean of its divisors is an integer number (5747258).

Almost surely, 2^251978688 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 251978688, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (402308060).

251978688 is an abundant number, since it is smaller than the sum of its proper divisors (552637432).

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

251978688 is a wasteful number, since it uses less digits than its factorization.

251978688 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3776 (or 3757 counting only the distinct ones).

The product of its digits is 1935360, while the sum is 54.

The square root of 251978688 is about 15873.8365872904. The cubic root of 251978688 is about 631.6181531452.

The spelling of 251978688 in words is "two hundred fifty-one million, nine hundred seventy-eight thousand, six hundred eighty-eight".