21266747 has 4 divisors (see below), whose sum is σ = 21285360. Its totient is φ = 21248136.

The previous prime is 21266737. The next prime is 21266753. The reversal of 21266747 is 74766212.

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 21266747 - 2⁴ = 21266731 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21266737) 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, 7472 + ... + 9917.

It is an arithmetic number, because the mean of its divisors is an integer number (5321340).

Almost surely, 2^21266747 is an apocalyptic number.

21266747 is a deficient number, since it is larger than the sum of its proper divisors (18613).

21266747 is a wasteful number, since it uses less digits than its factorization.

21266747 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 18612.

The product of its digits is 28224, while the sum is 35.

The square root of 21266747 is about 4611.5883380892. The cubic root of 21266747 is about 277.0556565995.

The spelling of 21266747 in words is "twenty-one million, two hundred sixty-six thousand, seven hundred forty-seven".