1251899989 has 6 divisors (see below), whose sum is σ = 1263758210. Its totient is φ = 1240048656.

The previous prime is 1251899983. The next prime is 1251900029. The reversal of 1251899989 is 9899981521.

It can be written as a sum of positive squares in 3 ways, for example, as 1001722500 + 250177489 = 31650^2 + 15817^2 .

It is not a de Polignac number, because 1251899989 - 2³ = 1251899981 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1251899981) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 367707 + ... + 371095.

Almost surely, 2^1251899989 is an apocalyptic number.

It is an amenable number.

1251899989 is a deficient number, since it is larger than the sum of its proper divisors (11858221).

1251899989 is an frugal number, since it uses more digits than its factorization.

1251899989 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6887 (or 3498 counting only the distinct ones).

The product of its digits is 4199040, while the sum is 61.

The square root of 1251899989 is about 35382.1987586979. The cubic root of 1251899989 is about 1077.7628556804.

The spelling of 1251899989 in words is "one billion, two hundred fifty-one million, eight hundred ninety-nine thousand, nine hundred eighty-nine".