21361664643 has 12 divisors (see below), whose sum is σ = 31306902984. Its totient is φ = 12946463200.

The previous prime is 21361664633. The next prime is 21361664689. The reversal of 21361664643 is 34646616312.

It is not a de Polignac number, because 21361664643 - 2⁹ = 21361664131 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21361664595 and 21361664604.

It is not an unprimeable number, because it can be changed into a prime (21361664633) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 29423418 + ... + 29424143.

It is an arithmetic number, because the mean of its divisors is an integer number (2608908582).

Almost surely, 2^21361664643 is an apocalyptic number.

21361664643 is a deficient number, since it is larger than the sum of its proper divisors (9945238341).

21361664643 is a wasteful number, since it uses less digits than its factorization.

21361664643 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 58847586 (or 58847575 counting only the distinct ones).

The product of its digits is 373248, while the sum is 42.

The spelling of 21361664643 in words is "twenty-one billion, three hundred sixty-one million, six hundred sixty-four thousand, six hundred forty-three".