21682723 has 4 divisors (see below), whose sum is σ = 21699288. Its totient is φ = 21666160.

The previous prime is 21682709. The next prime is 21682757. The reversal of 21682723 is 32728612.

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 21682723 - 2²¹ = 19585571 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21682223) 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, 6133 + ... + 8998.

It is an arithmetic number, because the mean of its divisors is an integer number (5424822).

Almost surely, 2^21682723 is an apocalyptic number.

21682723 is a deficient number, since it is larger than the sum of its proper divisors (16565).

21682723 is a wasteful number, since it uses less digits than its factorization.

21682723 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 16564.

The product of its digits is 8064, while the sum is 31.

The square root of 21682723 is about 4656.4710887108. The cubic root of 21682723 is about 278.8504013373.

The spelling of 21682723 in words is "twenty-one million, six hundred eighty-two thousand, seven hundred twenty-three".