21835890491 has 4 divisors (see below), whose sum is σ = 21838400184. Its totient is φ = 21833380800.

The previous prime is 21835890469. The next prime is 21835890509. The reversal of 21835890491 is 19409853812.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21835890491 is a prime.

It is a super-2 number, since 2×21835890491² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21835890191) 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 3 ways as a sum of consecutive naturals, for example, 1241750 + ... + 1259211.

It is an arithmetic number, because the mean of its divisors is an integer number (5459600046).

Almost surely, 2^21835890491 is an apocalyptic number.

21835890491 is a deficient number, since it is larger than the sum of its proper divisors (2509693).

21835890491 is an equidigital number, since it uses as much as digits as its factorization.

21835890491 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2509692.

The product of its (nonzero) digits is 622080, while the sum is 50.

The spelling of 21835890491 in words is "twenty-one billion, eight hundred thirty-five million, eight hundred ninety thousand, four hundred ninety-one".