1251020400 has 120 divisors (see below), whose sum is σ = 4579956864. Its totient is φ = 285945600.

The previous prime is 1251020399. The next prime is 1251020417. The reversal of 1251020400 is 40201521.

It is a tau number, because it is divible by the number of its divisors (120).

It is a Harshad number since it is a multiple of its sum of digits (15).

It is a self number, because there is not a number n which added to its sum of digits gives 1251020400.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 66066 + ... + 82865.

Almost surely, 2^1251020400 is an apocalyptic number.

1251020400 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

1251020400 is an abundant number, since it is smaller than the sum of its proper divisors (3328936464).

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

1251020400 is a wasteful number, since it uses less digits than its factorization.

1251020400 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 148959 (or 148948 counting only the distinct ones).

The product of its (nonzero) digits is 80, while the sum is 15.

The square root of 1251020400 is about 35369.7667507152. The cubic root of 1251020400 is about 1077.5103833138.

Adding to 1251020400 its reverse (40201521), we get a palindrome (1291221921).

The spelling of 1251020400 in words is "one billion, two hundred fifty-one million, twenty thousand, four hundred".