20865513601 has 27 divisors (see below), whose sum is σ = 23034379771. Its totient is φ = 18896240384.

The previous prime is 20865513587. The next prime is 20865513631. The reversal of 20865513601 is 10631556802.

The square root of 20865513601 is 144449.

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

It can be written as a sum of positive squares in 13 ways, for example, as 152547201 + 20712966400 = 12351^2 + 143920^2 .

It is not a de Polignac number, because 20865513601 - 2¹¹ = 20865511553 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20865513631) by changing a digit.

It is a polite number, since it can be written in 26 ways as a sum of consecutive naturals, for example, 71213211 + ... + 71213503.

Almost surely, 2^20865513601 is an apocalyptic number.

20865513601 is the 144449-th square number.

20865513601 is the 72225-th centered octagonal number.

It is an amenable number.

20865513601 is a deficient number, since it is larger than the sum of its proper divisors (2168866170).

20865513601 is an frugal number, since it uses more digits than its factorization.

20865513601 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 678 (or 339 counting only the distinct ones).

The product of its (nonzero) digits is 43200, while the sum is 37.

The spelling of 20865513601 in words is "twenty billion, eight hundred sixty-five million, five hundred thirteen thousand, six hundred one".