21766005 has 24 divisors (see below), whose sum is σ = 38109240. Its totient is φ = 11491200.

The previous prime is 21765983. The next prime is 21766007. The reversal of 21766005 is 50066712.

It can be written as a sum of positive squares in 4 ways, for example, as 2634129 + 19131876 = 1623^2 + 4374^2 .

It is not a de Polignac number, because 21766005 - 2¹⁴ = 21749621 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21766005.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21766007) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 2151 + ... + 6939.

It is an arithmetic number, because the mean of its divisors is an integer number (1587885).

Almost surely, 2^21766005 is an apocalyptic number.

It is an amenable number.

21766005 is a deficient number, since it is larger than the sum of its proper divisors (16343235).

21766005 is a wasteful number, since it uses less digits than its factorization.

21766005 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4901 (or 4898 counting only the distinct ones).

The product of its (nonzero) digits is 2520, while the sum is 27.

The square root of 21766005 is about 4665.4051271031. The cubic root of 21766005 is about 279.2069609420.

The spelling of 21766005 in words is "twenty-one million, seven hundred sixty-six thousand, five".