21557500843 has 6 divisors (see below), whose sum is σ = 22275337452. Its totient is φ = 20862096660.

The previous prime is 21557500837. The next prime is 21557500907. The reversal of 21557500843 is 34800575512.

It is a de Polignac number, because none of the positive numbers 2^k-21557500843 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21557500796 and 21557500805.

It is not an unprimeable number, because it can be changed into a prime (21557500043) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 11215221 + ... + 11217142.

It is an arithmetic number, because the mean of its divisors is an integer number (3712556242).

Almost surely, 2^21557500843 is an apocalyptic number.

21557500843 is a deficient number, since it is larger than the sum of its proper divisors (717836609).

21557500843 is an equidigital number, since it uses as much as digits as its factorization.

21557500843 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 22432425 (or 22432394 counting only the distinct ones).

The product of its (nonzero) digits is 168000, while the sum is 40.

The spelling of 21557500843 in words is "twenty-one billion, five hundred fifty-seven million, five hundred thousand, eight hundred forty-three".