21650723 has 4 divisors (see below), whose sum is σ = 21660048. Its totient is φ = 21641400.

The previous prime is 21650719. The next prime is 21650731. The reversal of 21650723 is 32705612.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It is a cyclic number.

It is not a de Polignac number, because 21650723 - 2² = 21650719 is a prime.

It is an alternating number because its digits alternate between even and odd.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21650692 and 21650701.

It is not an unprimeable number, because it can be changed into a prime (21650753) 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, 1898 + ... + 6848.

It is an arithmetic number, because the mean of its divisors is an integer number (5415012).

Almost surely, 2^21650723 is an apocalyptic number.

21650723 is a deficient number, since it is larger than the sum of its proper divisors (9325).

21650723 is an equidigital number, since it uses as much as digits as its factorization.

21650723 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9324.

The product of its (nonzero) digits is 2520, while the sum is 26.

The square root of 21650723 is about 4653.0337415497. The cubic root of 21650723 is about 278.7131552580.

The spelling of 21650723 in words is "twenty-one million, six hundred fifty thousand, seven hundred twenty-three".