21723307 has 2 divisors, whose sum is σ = 21723308. Its totient is φ = 21723306.

The previous prime is 21723301. The next prime is 21723311. The reversal of 21723307 is 70332712.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21723307 - 2¹⁹ = 21199019 is a prime.

It is not a weakly prime, because it can be changed into another prime (21723301) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10861653 + 10861654.

It is an arithmetic number, because the mean of its divisors is an integer number (10861654).

Almost surely, 2^21723307 is an apocalyptic number.

21723307 is a deficient number, since it is larger than the sum of its proper divisors (1).

21723307 is an equidigital number, since it uses as much as digits as its factorization.

21723307 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1764, while the sum is 25.

The square root of 21723307 is about 4660.8268579727. The cubic root of 21723307 is about 279.0242695879.

The spelling of 21723307 in words is "twenty-one million, seven hundred twenty-three thousand, three hundred seven".