251687066401 has 4 divisors (see below), whose sum is σ = 266492187972. Its totient is φ = 236881944832.

The previous prime is 251687066383. The next prime is 251687066419. The reversal of 251687066401 is 104660786152.

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

It is an interprime number because it is at equal distance from previous prime (251687066383) and next prime (251687066419).

It can be written as a sum of positive squares in 2 ways, for example, as 150005163025 + 101681903376 = 387305^2 + 318876^2 .

It is a cyclic number.

It is not a de Polignac number, because 251687066401 - 2¹⁹ = 251686542113 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (251687066431) 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, 7402560760 + ... + 7402560793.

It is an arithmetic number, because the mean of its divisors is an integer number (66623046993).

Almost surely, 2^251687066401 is an apocalyptic number.

It is an amenable number.

251687066401 is a deficient number, since it is larger than the sum of its proper divisors (14805121571).

251687066401 is a wasteful number, since it uses less digits than its factorization.

251687066401 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 14805121570.

The product of its (nonzero) digits is 483840, while the sum is 46.

It can be divided in two parts, 25168 and 7066401, that added together give a square (7091569 = 2663²).

The spelling of 251687066401 in words is "two hundred fifty-one billion, six hundred eighty-seven million, sixty-six thousand, four hundred one".