21292723 has 4 divisors (see below), whose sum is σ = 21868240. Its totient is φ = 20717208.

The previous prime is 21292717. The next prime is 21292729. The reversal of 21292723 is 32729212.

It is a semiprime because it is the product of two primes.

It is an interprime number because it is at equal distance from previous prime (21292717) and next prime (21292729).

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21292723 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 = 21292691 and 21292700.

It is not an unprimeable number, because it can be changed into a prime (21292729) 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 3 ways as a sum of consecutive naturals, for example, 287703 + ... + 287776.

It is an arithmetic number, because the mean of its divisors is an integer number (5467060).

Almost surely, 2^21292723 is an apocalyptic number.

21292723 is a deficient number, since it is larger than the sum of its proper divisors (575517).

21292723 is an equidigital number, since it uses as much as digits as its factorization.

21292723 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 575516.

The product of its digits is 3024, while the sum is 28.

The square root of 21292723 is about 4614.4038618222. The cubic root of 21292723 is about 277.1684127500.

The spelling of 21292723 in words is "twenty-one million, two hundred ninety-two thousand, seven hundred twenty-three".