251089661 has 2 divisors, whose sum is σ = 251089662. Its totient is φ = 251089660.

The previous prime is 251089639. The next prime is 251089679. The reversal of 251089661 is 166980152.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 248220025 + 2869636 = 15755^2 + 1694^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-251089661 is a prime.

It is a super-2 number, since 2×251089661² = 126092035722189842, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (251089621) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 125544830 + 125544831.

It is an arithmetic number, because the mean of its divisors is an integer number (125544831).

Almost surely, 2^251089661 is an apocalyptic number.

It is an amenable number.

251089661 is a deficient number, since it is larger than the sum of its proper divisors (1).

251089661 is an equidigital number, since it uses as much as digits as its factorization.

251089661 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 25920, while the sum is 38.

The square root of 251089661 is about 15845.8089411680. The cubic root of 251089661 is about 630.8744562844.

The spelling of 251089661 in words is "two hundred fifty-one million, eighty-nine thousand, six hundred sixty-one".