21766361 has 4 divisors (see below), whose sum is σ = 21864192. Its totient is φ = 21668532.

The previous prime is 21766351. The next prime is 21766363. The reversal of 21766361 is 16366712.

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 a de Polignac number, because none of the positive numbers 2^k-21766361 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21766363) 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, 48581 + ... + 49026.

It is an arithmetic number, because the mean of its divisors is an integer number (5466048).

Almost surely, 2^21766361 is an apocalyptic number.

It is an amenable number.

21766361 is a deficient number, since it is larger than the sum of its proper divisors (97831).

21766361 is an equidigital number, since it uses as much as digits as its factorization.

21766361 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 97830.

The product of its digits is 9072, while the sum is 32.

The square root of 21766361 is about 4665.4432801182. The cubic root of 21766361 is about 279.2084831496.

The spelling of 21766361 in words is "twenty-one million, seven hundred sixty-six thousand, three hundred sixty-one".