21366547 has 2 divisors, whose sum is σ = 21366548. Its totient is φ = 21366546.

The previous prime is 21366539. The next prime is 21366551. The reversal of 21366547 is 74566312.

It is a happy number.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21366547 - 2³ = 21366539 is a prime.

It is not a weakly prime, because it can be changed into another prime (21366557) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10683273 + 10683274.

It is an arithmetic number, because the mean of its divisors is an integer number (10683274).

Almost surely, 2^21366547 is an apocalyptic number.

21366547 is a deficient number, since it is larger than the sum of its proper divisors (1).

21366547 is an equidigital number, since it uses as much as digits as its factorization.

21366547 is an evil number, because the sum of its binary digits is even.

The product of its digits is 30240, while the sum is 34.

The square root of 21366547 is about 4622.3962400469. The cubic root of 21366547 is about 277.4883667985.

The spelling of 21366547 in words is "twenty-one million, three hundred sixty-six thousand, five hundred forty-seven".