20651905823 has 4 divisors (see below), whose sum is σ = 20942777808. Its totient is φ = 20361033840.

The previous prime is 20651905817. The next prime is 20651905831. The reversal of 20651905823 is 32850915602.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 20651905823 - 2⁸ = 20651905567 is a prime.

It is a super-2 number, since 2×20651905823² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20651905843) 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, 145435886 + ... + 145436027.

It is an arithmetic number, because the mean of its divisors is an integer number (5235694452).

Almost surely, 2^20651905823 is an apocalyptic number.

20651905823 is a deficient number, since it is larger than the sum of its proper divisors (290871985).

20651905823 is an equidigital number, since it uses as much as digits as its factorization.

20651905823 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 290871984.

The product of its (nonzero) digits is 129600, while the sum is 41.

The spelling of 20651905823 in words is "twenty billion, six hundred fifty-one million, nine hundred five thousand, eight hundred twenty-three".