21392723 has 8 divisors (see below), whose sum is σ = 23658096. Its totient is φ = 19180800.

The previous prime is 21392719. The next prime is 21392729. The reversal of 21392723 is 32729312.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21392723 - 2² = 21392719 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21392729) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 12518 + ... + 14123.

It is an arithmetic number, because the mean of its divisors is an integer number (2957262).

Almost surely, 2^21392723 is an apocalyptic number.

21392723 is a deficient number, since it is larger than the sum of its proper divisors (2265373).

21392723 is a wasteful number, since it uses less digits than its factorization.

21392723 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 26725.

The product of its digits is 4536, while the sum is 29.

The square root of 21392723 is about 4625.2268052497. The cubic root of 21392723 is about 277.6016368766.

The spelling of 21392723 in words is "twenty-one million, three hundred ninety-two thousand, seven hundred twenty-three".