1251721968 has 160 divisors (see below), whose sum is σ = 4039741440. Its totient is φ = 325693440.

The previous prime is 1251721967. The next prime is 1251721997. The reversal of 1251721968 is 8691271521.

It is a Harshad number since it is a multiple of its sum of digits (42).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1251721963) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 173538 + ... + 180606.

It is an arithmetic number, because the mean of its divisors is an integer number (25248384).

Almost surely, 2^1251721968 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 1251721968, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2019870720).

1251721968 is an abundant number, since it is smaller than the sum of its proper divisors (2788019472).

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

1251721968 is a wasteful number, since it uses less digits than its factorization.

1251721968 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7135 (or 7129 counting only the distinct ones).

The product of its digits is 60480, while the sum is 42.

The square root of 1251721968 is about 35379.6829833169. The cubic root of 1251721968 is about 1077.7117670636.

The spelling of 1251721968 in words is "one billion, two hundred fifty-one million, seven hundred twenty-one thousand, nine hundred sixty-eight".