251730981 has 12 divisors (see below), whose sum is σ = 382749120. Its totient is φ = 158987880.

The previous prime is 251730979. The next prime is 251730989. The reversal of 251730981 is 189037152.

It is not a de Polignac number, because 251730981 - 2¹ = 251730979 is a prime.

It is a super-2 number, since 2×251730981² = 126736973590444722, which contains 22 as substring.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (251730989) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 735885 + ... + 736226.

It is an arithmetic number, because the mean of its divisors is an integer number (31895760).

Almost surely, 2^251730981 is an apocalyptic number.

It is an amenable number.

251730981 is a deficient number, since it is larger than the sum of its proper divisors (131018139).

251730981 is a wasteful number, since it uses less digits than its factorization.

251730981 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1472136 (or 1472133 counting only the distinct ones).

The product of its (nonzero) digits is 15120, while the sum is 36.

The square root of 251730981 is about 15866.0323017445. The cubic root of 251730981 is about 631.4111150882.

The spelling of 251730981 in words is "two hundred fifty-one million, seven hundred thirty thousand, nine hundred eighty-one".