1215664657 has 8 divisors (see below), whose sum is σ = 1243797120. Its totient is φ = 1187724720.

The previous prime is 1215664613. The next prime is 1215664691. The reversal of 1215664657 is 7564665121.

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 1215664657 - 2¹⁹ = 1215140369 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1215667657) 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, 35319 + ... + 60652.

It is an arithmetic number, because the mean of its divisors is an integer number (155474640).

Almost surely, 2^1215664657 is an apocalyptic number.

It is an amenable number.

1215664657 is a deficient number, since it is larger than the sum of its proper divisors (28132463).

1215664657 is an equidigital number, since it uses as much as digits as its factorization.

1215664657 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 96263.

The product of its digits is 302400, while the sum is 43.

The square root of 1215664657 is about 34866.3829067484. The cubic root of 1215664657 is about 1067.2625331638.

The spelling of 1215664657 in words is "one billion, two hundred fifteen million, six hundred sixty-four thousand, six hundred fifty-seven".