251540216 has 8 divisors (see below), whose sum is σ = 471637920. Its totient is φ = 125770104.

The previous prime is 251540189. The next prime is 251540227. The reversal of 251540216 is 612045152.

It is a tau number, because it is divible by the number of its divisors (8).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 15721256 + ... + 15721271.

It is an arithmetic number, because the mean of its divisors is an integer number (58954740).

Almost surely, 2^251540216 is an apocalyptic number.

It is an amenable number.

251540216 is a deficient number, since it is larger than the sum of its proper divisors (220097704).

251540216 is a wasteful number, since it uses less digits than its factorization.

251540216 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 31442533 (or 31442529 counting only the distinct ones).

The product of its (nonzero) digits is 2400, while the sum is 26.

The square root of 251540216 is about 15860.0194199124. The cubic root of 251540216 is about 631.2515776061.

Adding to 251540216 its reverse (612045152), we get a palindrome (863585368).

The spelling of 251540216 in words is "two hundred fifty-one million, five hundred forty thousand, two hundred sixteen".