21682493921 has 16 divisors (see below), whose sum is σ = 24750904320. Its totient is φ = 18801744720.

The previous prime is 21682493909. The next prime is 21682493933. The reversal of 21682493921 is 12939428612.

It is a happy number.

It is an interprime number because it is at equal distance from previous prime (21682493909) and next prime (21682493933).

It is a de Polignac number, because none of the positive numbers 2^k-21682493921 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21682492921) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 28535 + ... + 210188.

It is an arithmetic number, because the mean of its divisors is an integer number (1546931520).

Almost surely, 2^21682493921 is an apocalyptic number.

It is an amenable number.

21682493921 is a deficient number, since it is larger than the sum of its proper divisors (3068410399).

21682493921 is a wasteful number, since it uses less digits than its factorization.

21682493921 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 239116.

The product of its digits is 373248, while the sum is 47.

The spelling of 21682493921 in words is "twenty-one billion, six hundred eighty-two million, four hundred ninety-three thousand, nine hundred twenty-one".