20537891665 has 8 divisors (see below), whose sum is σ = 24656148288. Its totient is φ = 16423194480.

The previous prime is 20537891663. The next prime is 20537891779. The reversal of 20537891665 is 56619873502.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 20537891665 - 2¹ = 20537891663 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20537891663) 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, 877147 + ... + 900256.

It is an arithmetic number, because the mean of its divisors is an integer number (3082018536).

Almost surely, 2^20537891665 is an apocalyptic number.

It is an amenable number.

20537891665 is a deficient number, since it is larger than the sum of its proper divisors (4118256623).

20537891665 is a wasteful number, since it uses less digits than its factorization.

20537891665 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1779719.

The product of its (nonzero) digits is 2721600, while the sum is 52.

The spelling of 20537891665 in words is "twenty billion, five hundred thirty-seven million, eight hundred ninety-one thousand, six hundred sixty-five".