251221535423 has 2 divisors, whose sum is σ = 251221535424. Its totient is φ = 251221535422.

The previous prime is 251221535401. The next prime is 251221535429. The reversal of 251221535423 is 324535122152.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 251221535423 - 2¹⁶ = 251221469887 is a prime.

It is a super-2 number, since 2×251221535423² (a number of 24 digits) contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (251221535429) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 125610767711 + 125610767712.

It is an arithmetic number, because the mean of its divisors is an integer number (125610767712).

Almost surely, 2^251221535423 is an apocalyptic number.

251221535423 is a deficient number, since it is larger than the sum of its proper divisors (1).

251221535423 is an equidigital number, since it uses as much as digits as its factorization.

251221535423 is an evil number, because the sum of its binary digits is even.

The product of its digits is 72000, while the sum is 35.

Adding to 251221535423 its reverse (324535122152), we get a palindrome (575756657575).

The spelling of 251221535423 in words is "two hundred fifty-one billion, two hundred twenty-one million, five hundred thirty-five thousand, four hundred twenty-three".