251611720325 has 24 divisors (see below), whose sum is σ = 356906085120. Its totient is φ = 172371009600.

The previous prime is 251611720319. The next prime is 251611720421. The reversal of 251611720325 is 523027116152.

It is not a de Polignac number, because 251611720325 - 2¹² = 251611716229 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (35).

It is a Curzon number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 491885 + ... + 863234.

It is an arithmetic number, because the mean of its divisors is an integer number (14871086880).

Almost surely, 2^251611720325 is an apocalyptic number.

251611720325 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

251611720325 is a deficient number, since it is larger than the sum of its proper divisors (105294364795).

251611720325 is a wasteful number, since it uses less digits than its factorization.

251611720325 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1356197 (or 1356192 counting only the distinct ones).

The product of its (nonzero) digits is 25200, while the sum is 35.

Adding to 251611720325 its reverse (523027116152), we get a palindrome (774638836477).

The spelling of 251611720325 in words is "two hundred fifty-one billion, six hundred eleven million, seven hundred twenty thousand, three hundred twenty-five".