251068661 has 4 divisors (see below), whose sum is σ = 251131692. Its totient is φ = 251005632.

The previous prime is 251068651. The next prime is 251068669. The reversal of 251068661 is 166860152.

It is a happy number.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 166539025 + 84529636 = 12905^2 + 9194^2 .

It is a cyclic number.

It is not a de Polignac number, because 251068661 - 2¹⁰ = 251067637 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (251068669) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 25106 + ... + 33651.

It is an arithmetic number, because the mean of its divisors is an integer number (62782923).

Almost surely, 2^251068661 is an apocalyptic number.

It is an amenable number.

251068661 is a deficient number, since it is larger than the sum of its proper divisors (63031).

251068661 is an equidigital number, since it uses as much as digits as its factorization.

251068661 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 63030.

The product of its (nonzero) digits is 17280, while the sum is 35.

The square root of 251068661 is about 15845.1462915304. The cubic root of 251068661 is about 630.8568679684.

The spelling of 251068661 in words is "two hundred fifty-one million, sixty-eight thousand, six hundred sixty-one".