21812723 has 2 divisors, whose sum is σ = 21812724. Its totient is φ = 21812722.

The previous prime is 21812711. The next prime is 21812731. The reversal of 21812723 is 32721812.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21812723 - 2⁸ = 21812467 is a prime.

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

It is a junction number, because it is equal to n+sod(n) for n = 21812692 and 21812701.

It is not a weakly prime, because it can be changed into another prime (21812783) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10906361 + 10906362.

It is an arithmetic number, because the mean of its divisors is an integer number (10906362).

Almost surely, 2^21812723 is an apocalyptic number.

21812723 is a deficient number, since it is larger than the sum of its proper divisors (1).

21812723 is an equidigital number, since it uses as much as digits as its factorization.

21812723 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 1344, while the sum is 26.

The square root of 21812723 is about 4670.4092968390. The cubic root of 21812723 is about 279.4065791001.

The spelling of 21812723 in words is "twenty-one million, eight hundred twelve thousand, seven hundred twenty-three".