251670661 has 4 divisors (see below), whose sum is σ = 274549824. Its totient is φ = 228791500.

The previous prime is 251670611. The next prime is 251670697. The reversal of 251670661 is 166076152.

It is a happy number.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-251670661 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 (251670611) 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, 11439565 + ... + 11439586.

It is an arithmetic number, because the mean of its divisors is an integer number (68637456).

Almost surely, 2^251670661 is an apocalyptic number.

It is an amenable number.

251670661 is a deficient number, since it is larger than the sum of its proper divisors (22879163).

251670661 is a wasteful number, since it uses less digits than its factorization.

251670661 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 22879162.

The product of its (nonzero) digits is 15120, while the sum is 34.

The square root of 251670661 is about 15864.1312715194. The cubic root of 251670661 is about 631.3606779631.

The spelling of 251670661 in words is "two hundred fifty-one million, six hundred seventy thousand, six hundred sixty-one".