1251138601887 has 4 divisors (see below), whose sum is σ = 1668184802520. Its totient is φ = 834092401256.

The previous prime is 1251138601883. The next prime is 1251138601913. The reversal of 1251138601887 is 7881068311521.

It is a happy number.

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 1251138601887 - 2² = 1251138601883 is a prime.

It is a super-2 number, since 2×1251138601887² (a number of 25 digits) contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1251138601883) 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, 208523100312 + ... + 208523100317.

It is an arithmetic number, because the mean of its divisors is an integer number (417046200630).

Almost surely, 2^{1251138601887} is an apocalyptic number.

1251138601887 is a deficient number, since it is larger than the sum of its proper divisors (417046200633).

1251138601887 is an equidigital number, since it uses as much as digits as its factorization.

1251138601887 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 417046200632.

The product of its (nonzero) digits is 645120, while the sum is 51.

The spelling of 1251138601887 in words is "one trillion, two hundred fifty-one billion, one hundred thirty-eight million, six hundred one thousand, eight hundred eighty-seven".