21266723 has 4 divisors (see below), whose sum is σ = 21285000. Its totient is φ = 21248448.

The previous prime is 21266669. The next prime is 21266731. The reversal of 21266723 is 32766212.

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

It is a cyclic number.

It is not a de Polignac number, because 21266723 - 2¹² = 21262627 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21266753) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 7265 + ... + 9762.

It is an arithmetic number, because the mean of its divisors is an integer number (5321250).

Almost surely, 2^21266723 is an apocalyptic number.

21266723 is a deficient number, since it is larger than the sum of its proper divisors (18277).

21266723 is a wasteful number, since it uses less digits than its factorization.

21266723 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 18276.

The product of its digits is 6048, while the sum is 29.

The square root of 21266723 is about 4611.5857359481. The cubic root of 21266723 is about 277.0555523783.

The spelling of 21266723 in words is "twenty-one million, two hundred sixty-six thousand, seven hundred twenty-three".