1251999999 has 12 divisors (see below), whose sum is σ = 1808778400. Its totient is φ = 834512544.

The previous prime is 1251999967. The next prime is 1252000027. The reversal of 1251999999 is 9999991521.

It is not a de Polignac number, because 1251999999 - 2⁵ = 1251999967 is a prime.

It is a Duffinian number.

1251999999 is a modest number, since divided by 99999 gives 12519 as remainder.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1251999949) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 60867 + ... + 78795.

Almost surely, 2^1251999999 is an apocalyptic number.

1251999999 is a deficient number, since it is larger than the sum of its proper divisors (556778401).

1251999999 is a wasteful number, since it uses less digits than its factorization.

1251999999 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 25694 (or 25691 counting only the distinct ones).

The product of its digits is 5314410, while the sum is 63.

The square root of 1251999999 is about 35383.6120117774. The cubic root of 1251999999 is about 1077.7915545099.

The spelling of 1251999999 in words is "one billion, two hundred fifty-one million, nine hundred ninety-nine thousand, nine hundred ninety-nine".