1215857664 has 264 divisors, whose sum is σ = 4107886848. Its totient is φ = 339148800.

The previous prime is 1215857659. The next prime is 1215857681. The reversal of 1215857664 is 4667585121.

1215857664 is a `hidden beast` number, since 1 + 2 + 1 + 585 + 7 + 6 + 64 = 666.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 3031864 + ... + 3032264.

Almost surely, 2^1215857664 is an apocalyptic number.

1215857664 is a gapful number since it is divisible by the number (14) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 1215857664, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2053943424).

1215857664 is an abundant number, since it is smaller than the sum of its proper divisors (2892029184).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

1215857664 is a wasteful number, since it uses less digits than its factorization.

1215857664 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 481 (or 460 counting only the distinct ones).

The product of its digits is 403200, while the sum is 45.

The square root of 1215857664 is about 34869.1506062307. The cubic root of 1215857664 is about 1067.3190120724.

The spelling of 1215857664 in words is "one billion, two hundred fifteen million, eight hundred fifty-seven thousand, six hundred sixty-four".