1215975121 has 4 divisors (see below), whose sum is σ = 1216172644. Its totient is φ = 1215777600.

The previous prime is 1215975119. The next prime is 1215975169. The reversal of 1215975121 is 1215795121.

It is a happy number.

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

It can be written as a sum of positive squares in 2 ways, for example, as 798345025 + 417630096 = 28255^2 + 20436^2 .

It is a cyclic number.

It is not a de Polignac number, because 1215975121 - 2¹ = 1215975119 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1215975221) 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, 89220 + ... + 101941.

It is an arithmetic number, because the mean of its divisors is an integer number (304043161).

Almost surely, 2^1215975121 is an apocalyptic number.

It is an amenable number.

1215975121 is a deficient number, since it is larger than the sum of its proper divisors (197523).

1215975121 is an equidigital number, since it uses as much as digits as its factorization.

1215975121 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 197522.

The product of its digits is 6300, while the sum is 34.

The square root of 1215975121 is about 34870.8348193731. The cubic root of 1215975121 is about 1067.3533801448.

The spelling of 1215975121 in words is "one billion, two hundred fifteen million, nine hundred seventy-five thousand, one hundred twenty-one".