20995531665 has 16 divisors (see below), whose sum is σ = 34676491776. Its totient is φ = 10836403200.

The previous prime is 20995531663. The next prime is 20995531673. The reversal of 20995531665 is 56613559902.

It is not a de Polignac number, because 20995531665 - 2¹ = 20995531663 is a prime.

It is not an unprimeable number, because it can be changed into a prime (20995531663) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 22575376 + ... + 22576305.

It is an arithmetic number, because the mean of its divisors is an integer number (2167280736).

Almost surely, 2^20995531665 is an apocalyptic number.

It is an amenable number.

20995531665 is a deficient number, since it is larger than the sum of its proper divisors (13680960111).

20995531665 is a wasteful number, since it uses less digits than its factorization.

20995531665 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 45151720.

The product of its (nonzero) digits is 2187000, while the sum is 51.

The spelling of 20995531665 in words is "twenty billion, nine hundred ninety-five million, five hundred thirty-one thousand, six hundred sixty-five".