21966645 has 16 divisors (see below), whose sum is σ = 35811072. Its totient is φ = 11494080.

The previous prime is 21966643. The next prime is 21966647. The reversal of 21966645 is 54666912.

It is an interprime number because it is at equal distance from previous prime (21966643) and next prime (21966647).

It is not a de Polignac number, because 21966645 - 2¹ = 21966643 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21966643) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 13021 + ... + 14610.

It is an arithmetic number, because the mean of its divisors is an integer number (2238192).

Almost surely, 2^21966645 is an apocalyptic number.

It is an amenable number.

21966645 is a deficient number, since it is larger than the sum of its proper divisors (13844427).

21966645 is a wasteful number, since it uses less digits than its factorization.

21966645 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 27692.

The product of its digits is 77760, while the sum is 39.

The square root of 21966645 is about 4686.8587561393. The cubic root of 21966645 is about 280.0622523149.

The spelling of 21966645 in words is "twenty-one million, nine hundred sixty-six thousand, six hundred forty-five".