21799985 has 8 divisors (see below), whose sum is σ = 26232360. Its totient is φ = 17391744.

The previous prime is 21799979. The next prime is 21800003. The reversal of 21799985 is 58999712.

It is a happy number.

It can be written as a sum of positive squares in 4 ways, for example, as 8832784 + 12967201 = 2972^2 + 3601^2 .

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

It is a cyclic number.

It is not a de Polignac number, because 21799985 - 2¹⁰ = 21798961 is a prime.

It is a Curzon 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, 3980 + ... + 7709.

It is an arithmetic number, because the mean of its divisors is an integer number (3279045).

Almost surely, 2^21799985 is an apocalyptic number.

It is an amenable number.

21799985 is a deficient number, since it is larger than the sum of its proper divisors (4432375).

21799985 is a wasteful number, since it uses less digits than its factorization.

21799985 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 12067.

The product of its digits is 408240, while the sum is 50.

The square root of 21799985 is about 4669.0454056477. The cubic root of 21799985 is about 279.3521800531.

The spelling of 21799985 in words is "twenty-one million, seven hundred ninety-nine thousand, nine hundred eighty-five".