1215121251 has 4 divisors (see below), whose sum is σ = 1620161672. Its totient is φ = 810080832.

The previous prime is 1215121247. The next prime is 1215121267. The reversal of 1215121251 is 1521215121.

It is a semiprime because it is the product of two primes.

It is not a de Polignac number, because 1215121251 - 2² = 1215121247 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1215121241) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 202520206 + ... + 202520211.

It is an arithmetic number, because the mean of its divisors is an integer number (405040418).

Almost surely, 2^1215121251 is an apocalyptic number.

1215121251 is a deficient number, since it is larger than the sum of its proper divisors (405040421).

1215121251 is an equidigital number, since it uses as much as digits as its factorization.

1215121251 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 405040420.

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

The square root of 1215121251 is about 34858.5893432307. The cubic root of 1215121251 is about 1067.1034862050.

Adding to 1215121251 its reverse (1521215121), we get a palindrome (2736336372).

The spelling of 1215121251 in words is "one billion, two hundred fifteen million, one hundred twenty-one thousand, two hundred fifty-one".