1251521103 has 48 divisors (see below), whose sum is σ = 2036897280. Its totient is φ = 680226624.

The previous prime is 1251521099. The next prime is 1251521137. The reversal of 1251521103 is 3011251521.

It is not a de Polignac number, because 1251521103 - 2² = 1251521099 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (21).

It is a self number, because there is not a number n which added to its sum of digits gives 1251521103.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1251521153) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 665118 + ... + 666996.

It is an arithmetic number, because the mean of its divisors is an integer number (42435360).

Almost surely, 2^1251521103 is an apocalyptic number.

1251521103 is a deficient number, since it is larger than the sum of its proper divisors (785376177).

1251521103 is a wasteful number, since it uses less digits than its factorization.

1251521103 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2116 (or 2109 counting only the distinct ones).

The product of its (nonzero) digits is 300, while the sum is 21.

The square root of 1251521103 is about 35376.8441639443. The cubic root of 1251521103 is about 1077.6541168399.

Adding to 1251521103 its reverse (3011251521), we get a palindrome (4262772624).

The spelling of 1251521103 in words is "one billion, two hundred fifty-one million, five hundred twenty-one thousand, one hundred three".