21557860903 has 2 divisors, whose sum is σ = 21557860904. Its totient is φ = 21557860902.

The previous prime is 21557860847. The next prime is 21557861021. The reversal of 21557860903 is 30906875512.

It is a weak prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21557860903 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21557660903) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10778930451 + 10778930452.

It is an arithmetic number, because the mean of its divisors is an integer number (10778930452).

Almost surely, 2^21557860903 is an apocalyptic number.

21557860903 is a deficient number, since it is larger than the sum of its proper divisors (1).

21557860903 is an equidigital number, since it uses as much as digits as its factorization.

21557860903 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 453600, while the sum is 46.

The spelling of 21557860903 in words is "twenty-one billion, five hundred fifty-seven million, eight hundred sixty thousand, nine hundred three".