1215242251 has 4 divisors (see below), whose sum is σ = 1215664632. Its totient is φ = 1214819872.

The previous prime is 1215242243. The next prime is 1215242257. The reversal of 1215242251 is 1522425121.

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

It is a cyclic number.

It is not a de Polignac number, because 1215242251 - 2³ = 1215242243 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1215242257) 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, 206845 + ... + 212638.

It is an arithmetic number, because the mean of its divisors is an integer number (303916158).

Almost surely, 2^1215242251 is an apocalyptic number.

1215242251 is a deficient number, since it is larger than the sum of its proper divisors (422381).

1215242251 is an equidigital number, since it uses as much as digits as its factorization.

1215242251 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 422380.

The product of its digits is 1600, while the sum is 25.

The square root of 1215242251 is about 34860.3248837414. The cubic root of 1215242251 is about 1067.1389052317.

Adding to 1215242251 its reverse (1522425121), we get a palindrome (2737667372).

The spelling of 1215242251 in words is "one billion, two hundred fifteen million, two hundred forty-two thousand, two hundred fifty-one".