21402723 has 6 divisors (see below), whose sum is σ = 28547652. Its totient is φ = 14263140.

The previous prime is 21402713. The next prime is 21402739. The reversal of 21402723 is 32720412.

It is not a de Polignac number, because 21402723 - 2⁸ = 21402467 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21402723.

It is not an unprimeable number, because it can be changed into a prime (21402713) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 6678 + ... + 9348.

It is an arithmetic number, because the mean of its divisors is an integer number (4757942).

Almost surely, 2^21402723 is an apocalyptic number.

21402723 is a deficient number, since it is larger than the sum of its proper divisors (7144929).

21402723 is an frugal number, since it uses more digits than its factorization.

21402723 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5345 (or 2674 counting only the distinct ones).

The product of its (nonzero) digits is 672, while the sum is 21.

The square root of 21402723 is about 4626.3077070165. The cubic root of 21402723 is about 277.6448849775.

The spelling of 21402723 in words is "twenty-one million, four hundred two thousand, seven hundred twenty-three".