1251257506399 has 4 divisors (see below), whose sum is σ = 1251265948240. Its totient is φ = 1251249064560.

The previous prime is 1251257506397. The next prime is 1251257506423. The reversal of 1251257506399 is 9936057521521.

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

It is a cyclic number.

It is not a de Polignac number, because 1251257506399 - 2¹ = 1251257506397 is a prime.

It is a super-3 number, since 3×1251257506399³ (a number of 37 digits) contains 333 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1251257506397) 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, 3994542 + ... + 4296379.

It is an arithmetic number, because the mean of its divisors is an integer number (312816487060).

Almost surely, 2^{1251257506399} is an apocalyptic number.

1251257506399 is a deficient number, since it is larger than the sum of its proper divisors (8441841).

1251257506399 is an equidigital number, since it uses as much as digits as its factorization.

1251257506399 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8441840.

The product of its (nonzero) digits is 5103000, while the sum is 55.

The spelling of 1251257506399 in words is "one trillion, two hundred fifty-one billion, two hundred fifty-seven million, five hundred six thousand, three hundred ninety-nine".