1251000000 has 294 divisors, whose sum is σ = 4514395340. Its totient is φ = 331200000.

The previous prime is 1250999983. The next prime is 1251000001. The reversal of 1251000000 is 1521.

It is a happy number.

It is a Harshad number since it is a multiple of its sum of digits (9).

It is not an unprimeable number, because it can be changed into a prime (1251000001) 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 41 ways as a sum of consecutive naturals, for example, 8999931 + ... + 9000069.

Almost surely, 2^1251000000 is an apocalyptic number.

1251000000 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 1251000000, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2257197670).

1251000000 is an abundant number, since it is smaller than the sum of its proper divisors (3263395340).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

1251000000 is an frugal number, since it uses more digits than its factorization.

1251000000 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 187 (or 149 counting only the distinct ones).

The product of its (nonzero) digits is 10, while the sum is 9.

The square root of 1251000000 is about 35369.4783676548. The cubic root of 1251000000 is about 1077.5045264065.

Adding to 1251000000 its reverse (1521), we get a palindrome (1251001521).

The spelling of 1251000000 in words is "one billion, two hundred fifty-one million", and thus it is an aban number.