251343661 has 2 divisors, whose sum is σ = 251343662. Its totient is φ = 251343660.

The previous prime is 251343637. The next prime is 251343683. The reversal of 251343661 is 166343152.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 222934761 + 28408900 = 14931^2 + 5330^2 .

It is a cyclic number.

It is not a de Polignac number, because 251343661 - 2²¹ = 249246509 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (251343611) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 125671830 + 125671831.

It is an arithmetic number, because the mean of its divisors is an integer number (125671831).

Almost surely, 2^251343661 is an apocalyptic number.

It is an amenable number.

251343661 is a deficient number, since it is larger than the sum of its proper divisors (1).

251343661 is an equidigital number, since it uses as much as digits as its factorization.

251343661 is an evil number, because the sum of its binary digits is even.

The product of its digits is 12960, while the sum is 31.

The square root of 251343661 is about 15853.8216528382. The cubic root of 251343661 is about 631.0871135326.

It can be divided in two parts, 251343 and 661, that added together give a square (252004 = 502²).

The spelling of 251343661 in words is "two hundred fifty-one million, three hundred forty-three thousand, six hundred sixty-one".