21492723 has 16 divisors (see below), whose sum is σ = 33420800. Its totient is φ = 12280968.

The previous prime is 21492659. The next prime is 21492727. The reversal of 21492723 is 32729412.

It is not a de Polignac number, because 21492723 - 2⁶ = 21492659 is a prime.

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

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21492727) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 9415 + ... + 11472.

It is an arithmetic number, because the mean of its divisors is an integer number (2088800).

Almost surely, 2^21492723 is an apocalyptic number.

21492723 is a deficient number, since it is larger than the sum of its proper divisors (11928077).

21492723 is an equidigital number, since it uses as much as digits as its factorization.

21492723 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 20911 (or 20897 counting only the distinct ones).

The product of its digits is 6048, while the sum is 30.

The square root of 21492723 is about 4636.0244822477. The cubic root of 21492723 is about 278.0335130311.

The spelling of 21492723 in words is "twenty-one million, four hundred ninety-two thousand, seven hundred twenty-three".