21880565 has 16 divisors (see below), whose sum is σ = 30101760. Its totient is φ = 14956800.

The previous prime is 21880559. The next prime is 21880583. The reversal of 21880565 is 56508812.

It is a happy number.

It is not a de Polignac number, because 21880565 - 2⁴ = 21880549 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (35).

It is a Curzon number.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 13256 + ... + 14814.

It is an arithmetic number, because the mean of its divisors is an integer number (1881360).

Almost surely, 2^21880565 is an apocalyptic number.

It is an amenable number.

21880565 is a deficient number, since it is larger than the sum of its proper divisors (8221195).

21880565 is a wasteful number, since it uses less digits than its factorization.

21880565 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1972.

The product of its (nonzero) digits is 19200, while the sum is 35.

The square root of 21880565 is about 4677.6666191596. Note that the first 4 decimals coincide. The cubic root of 21880565 is about 279.6959497151.

The spelling of 21880565 in words is "twenty-one million, eight hundred eighty thousand, five hundred sixty-five".