251131520205997 has 2 divisors, whose sum is σ = 251131520205998. Its totient is φ = 251131520205996.

The previous prime is 251131520205991. The next prime is 251131520206051. The reversal of 251131520205997 is 799502025131152.

It is a happy number.

251131520205997 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 171136133773801 + 79995386432196 = 13081901^2 + 8944014^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-251131520205997 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (251131520205991) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 125565760102998 + 125565760102999.

It is an arithmetic number, because the mean of its divisors is an integer number (125565760102999).

Almost surely, 2^{251131520205997} is an apocalyptic number.

It is an amenable number.

251131520205997 is a deficient number, since it is larger than the sum of its proper divisors (1).

251131520205997 is an equidigital number, since it uses as much as digits as its factorization.

251131520205997 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1701000, while the sum is 52.

The spelling of 251131520205997 in words is "two hundred fifty-one trillion, one hundred thirty-one billion, five hundred twenty million, two hundred five thousand, nine hundred ninety-seven".