21860805 has 16 divisors (see below), whose sum is σ = 35074944. Its totient is φ = 11626560.

The previous prime is 21860791. The next prime is 21860819. The reversal of 21860805 is 50806812.

It is an interprime number because it is at equal distance from previous prime (21860791) and next prime (21860819).

It is a de Polignac number, because none of the positive numbers 2^k-21860805 is a prime.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 4120 + ... + 7790.

It is an arithmetic number, because the mean of its divisors is an integer number (2192184).

Almost surely, 2^21860805 is an apocalyptic number.

It is an amenable number.

21860805 is a deficient number, since it is larger than the sum of its proper divisors (13214139).

21860805 is a wasteful number, since it uses less digits than its factorization.

21860805 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4076.

The product of its (nonzero) digits is 3840, while the sum is 30.

The square root of 21860805 is about 4675.5539778726. The cubic root of 21860805 is about 279.6117279941.

The spelling of 21860805 in words is "twenty-one million, eight hundred sixty thousand, eight hundred five".