251217997563 has 72 divisors (see below), whose sum is σ = 377757536256. Its totient is φ = 148280932800.

The previous prime is 251217997561. The next prime is 251217997601. The reversal of 251217997563 is 365799712152.

It is a happy number.

It is not a de Polignac number, because 251217997563 - 2¹ = 251217997561 is a prime.

It is a super-2 number, since 2×251217997563² (a number of 24 digits) contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (251217997561) by changing a digit.

It is a polite number, since it can be written in 71 ways as a sum of consecutive naturals, for example, 253498998 + ... + 253499988.

It is an arithmetic number, because the mean of its divisors is an integer number (5246632448).

Almost surely, 2^251217997563 is an apocalyptic number.

251217997563 is a deficient number, since it is larger than the sum of its proper divisors (126539538693).

251217997563 is a wasteful number, since it uses less digits than its factorization.

251217997563 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1305 (or 1165 counting only the distinct ones).

The product of its digits is 7144200, while the sum is 57.

The spelling of 251217997563 in words is "two hundred fifty-one billion, two hundred seventeen million, nine hundred ninety-seven thousand, five hundred sixty-three".