21990785 has 8 divisors (see below), whose sum is σ = 26528256. Its totient is φ = 17499760.

The previous prime is 21990769. The next prime is 21990791. The reversal of 21990785 is 58709912.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 21990785 - 2⁴ = 21990769 is a prime.

It is a Duffinian number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 10559 + ... + 12468.

It is an arithmetic number, because the mean of its divisors is an integer number (3316032).

Almost surely, 2^21990785 is an apocalyptic number.

It is an amenable number.

21990785 is a deficient number, since it is larger than the sum of its proper divisors (4537471).

21990785 is a wasteful number, since it uses less digits than its factorization.

21990785 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 23223.

The product of its (nonzero) digits is 45360, while the sum is 41.

The square root of 21990785 is about 4689.4333346365. The cubic root of 21990785 is about 280.1648051892.

The spelling of 21990785 in words is "twenty-one million, nine hundred ninety thousand, seven hundred eighty-five".