1251521121 has 4 divisors (see below), whose sum is σ = 1668694832. Its totient is φ = 834347412.

The previous prime is 1251521099. The next prime is 1251521137. The reversal of 1251521121 is 1211251521.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is not a de Polignac number, because 1251521121 - 2⁷ = 1251520993 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1251521021) 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 3 ways as a sum of consecutive naturals, for example, 208586851 + ... + 208586856.

It is an arithmetic number, because the mean of its divisors is an integer number (417173708).

Almost surely, 2^1251521121 is an apocalyptic number.

It is an amenable number.

1251521121 is a deficient number, since it is larger than the sum of its proper divisors (417173711).

1251521121 is an equidigital number, since it uses as much as digits as its factorization.

1251521121 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 417173710.

The product of its digits is 200, while the sum is 21.

The square root of 1251521121 is about 35376.8444183480. The cubic root of 1251521121 is about 1077.6541220063.

Adding to 1251521121 its reverse (1211251521), we get a palindrome (2462772642).

The spelling of 1251521121 in words is "one billion, two hundred fifty-one million, five hundred twenty-one thousand, one hundred twenty-one".