21366361 has 4 divisors (see below), whose sum is σ = 21456000. Its totient is φ = 21276724.

The previous prime is 21366343. The next prime is 21366377. The reversal of 21366361 is 16366312.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 21366361 - 2⁵ = 21366329 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21366311) 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, 44461 + ... + 44938.

It is an arithmetic number, because the mean of its divisors is an integer number (5364000).

Almost surely, 2^21366361 is an apocalyptic number.

It is an amenable number.

21366361 is a deficient number, since it is larger than the sum of its proper divisors (89639).

21366361 is an equidigital number, since it uses as much as digits as its factorization.

21366361 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 89638.

The product of its digits is 3888, while the sum is 28.

The square root of 21366361 is about 4622.3761205683. The cubic root of 21366361 is about 277.4875615992.

The spelling of 21366361 in words is "twenty-one million, three hundred sixty-six thousand, three hundred sixty-one".