251640001 has 8 divisors (see below), whose sum is σ = 272941704. Its totient is φ = 231060480.

The previous prime is 251639977. The next prime is 251640023. The reversal of 251640001 is 100046152.

It can be written as a sum of positive squares in 4 ways, for example, as 65999376 + 185640625 = 8124^2 + 13625^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-251640001 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (251640041) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 179820 + ... + 181213.

It is an arithmetic number, because the mean of its divisors is an integer number (34117713).

Almost surely, 2^251640001 is an apocalyptic number.

It is an amenable number.

251640001 is a deficient number, since it is larger than the sum of its proper divisors (21301703).

251640001 is a wasteful number, since it uses less digits than its factorization.

251640001 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 361091.

The product of its (nonzero) digits is 240, while the sum is 19.

The square root of 251640001 is about 15863.1649112023. The cubic root of 251640001 is about 631.3350382316.

Adding to 251640001 its reverse (100046152), we get a palindrome (351686153).

The spelling of 251640001 in words is "two hundred fifty-one million, six hundred forty thousand, one".