21403444643 has 4 divisors (see below), whose sum is σ = 24461079600. Its totient is φ = 18345809688.

The previous prime is 21403444637. The next prime is 21403444663. The reversal of 21403444643 is 34644430412.

It is a happy number.

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 21403444643 - 2²² = 21399250339 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21403444663) 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, 1528817468 + ... + 1528817481.

It is an arithmetic number, because the mean of its divisors is an integer number (6115269900).

Almost surely, 2^21403444643 is an apocalyptic number.

21403444643 is a deficient number, since it is larger than the sum of its proper divisors (3057634957).

21403444643 is an equidigital number, since it uses as much as digits as its factorization.

21403444643 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3057634956.

The product of its (nonzero) digits is 110592, while the sum is 35.

The spelling of 21403444643 in words is "twenty-one billion, four hundred three million, four hundred forty-four thousand, six hundred forty-three".