1215561187697 has 8 divisors (see below), whose sum is σ = 1252411998120. Its totient is φ = 1179225773440.

The previous prime is 1215561187693. The next prime is 1215561187747. The reversal of 1215561187697 is 7967811655121.

It can be written as a sum of positive squares in 4 ways, for example, as 46117681 + 1215515070016 = 6791^2 + 1102504^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 1215561187697 - 2² = 1215561187693 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1215561187693) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 128844254 + ... + 128853687.

It is an arithmetic number, because the mean of its divisors is an integer number (156551499765).

Almost surely, 2^{1215561187697} is an apocalyptic number.

It is an amenable number.

1215561187697 is a deficient number, since it is larger than the sum of its proper divisors (36850810423).

1215561187697 is an equidigital number, since it uses as much as digits as its factorization.

1215561187697 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 257698083.

The product of its digits is 6350400, while the sum is 59.

The spelling of 1215561187697 in words is "one trillion, two hundred fifteen billion, five hundred sixty-one million, one hundred eighty-seven thousand, six hundred ninety-seven".