615896913681 has 45 divisors (see below), whose sum is σ = 1070340650379. Its totient is φ = 351912841056.

The previous prime is 615896913673. The next prime is 615896913707. The reversal of 615896913681 is 186319698516.

The square root of 615896913681 is 784791.

It is a perfect power (a square), and thus also a powerful number.

615896913681 is a `hidden beast` number, since 615 + 8 + 9 + 6 + 9 + 1 + 3 + 6 + 8 + 1 = 666.

It can be written as a sum of positive squares in only one way, i.e., 507250206225 + 108646707456 = 712215^2 + 329616^2 .

It is not a de Polignac number, because 615896913681 - 2³ = 615896913673 is a prime.

It is a super-2 number, since 2×615896913681² (a number of 24 digits) contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (63).

It is not an unprimeable number, because it can be changed into a prime (615896913631) by changing a digit.

It is a polite number, since it can be written in 44 ways as a sum of consecutive naturals, for example, 49435605 + ... + 49448061.

Almost surely, 2^615896913681 is an apocalyptic number.

615896913681 is the 784791-st square number.

615896913681 is the 392396-th centered octagonal number.

It is an amenable number.

615896913681 is a deficient number, since it is larger than the sum of its proper divisors (454443736698).

615896913681 is an frugal number, since it uses more digits than its factorization.

615896913681 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 24940 (or 12467 counting only the distinct ones).

The product of its digits is 16796160, while the sum is 63.

The spelling of 615896913681 in words is "six hundred fifteen billion, eight hundred ninety-six million, nine hundred thirteen thousand, six hundred eighty-one".