20856644903 has 2 divisors, whose sum is σ = 20856644904. Its totient is φ = 20856644902.

The previous prime is 20856644873. The next prime is 20856644923. The reversal of 20856644903 is 30944665802.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 20856644903 - 2⁶ = 20856644839 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20856644923) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10428322451 + 10428322452.

It is an arithmetic number, because the mean of its divisors is an integer number (10428322452).

Almost surely, 2^20856644903 is an apocalyptic number.

20856644903 is a deficient number, since it is larger than the sum of its proper divisors (1).

20856644903 is an equidigital number, since it uses as much as digits as its factorization.

20856644903 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1244160, while the sum is 47.

The spelling of 20856644903 in words is "twenty billion, eight hundred fifty-six million, six hundred forty-four thousand, nine hundred three".