251994681 has 6 divisors (see below), whose sum is σ = 363992330. Its totient is φ = 167996448.

The previous prime is 251994671. The next prime is 251994703. The reversal of 251994681 is 186499152.

251994681 is nontrivially palindromic in base 8.

It can be written as a sum of positive squares in only one way, i.e., 236667456 + 15327225 = 15384^2 + 3915^2 .

It is not a de Polignac number, because 251994681 - 2¹³ = 251986489 is a prime.

It is a super-2 number, since 2×251994681² = 127002638504583522, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (251994671) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 13999696 + ... + 13999713.

Almost surely, 2^251994681 is an apocalyptic number.

It is an amenable number.

251994681 is a deficient number, since it is larger than the sum of its proper divisors (111997649).

251994681 is a wasteful number, since it uses less digits than its factorization.

251994681 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 27999415 (or 27999412 counting only the distinct ones).

The product of its digits is 155520, while the sum is 45.

The square root of 251994681 is about 15874.3403327508. The cubic root of 251994681 is about 631.6315157242.

The spelling of 251994681 in words is "two hundred fifty-one million, nine hundred ninety-four thousand, six hundred eighty-one".