20500665121 has 4 divisors (see below), whose sum is σ = 20501539632. Its totient is φ = 20499790612.

The previous prime is 20500665091. The next prime is 20500665169. The reversal of 20500665121 is 12156600502.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 20500665121 - 2¹³ = 20500656929 is a prime.

It is a super-3 number, since 3×20500665121³ (a number of 32 digits) contains 333 as substring.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 20500665121.

It is not an unprimeable number, because it can be changed into a prime (20500665421) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 401095 + ... + 449308.

It is an arithmetic number, because the mean of its divisors is an integer number (5125384908).

Almost surely, 2^20500665121 is an apocalyptic number.

It is an amenable number.

20500665121 is a deficient number, since it is larger than the sum of its proper divisors (874511).

20500665121 is an equidigital number, since it uses as much as digits as its factorization.

20500665121 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 874510.

The product of its (nonzero) digits is 3600, while the sum is 28.

The spelling of 20500665121 in words is "twenty billion, five hundred million, six hundred sixty-five thousand, one hundred twenty-one".