20021765 has 8 divisors (see below), whose sum is σ = 24537600. Its totient is φ = 15676432.

The previous prime is 20021759. The next prime is 20021821. The reversal of 20021765 is 56712002.

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 20021765 - 2²⁰ = 18973189 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 20021765.

It is a congruent 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, 42365 + ... + 42834.

It is an arithmetic number, because the mean of its divisors is an integer number (3067200).

Almost surely, 2^20021765 is an apocalyptic number.

It is an amenable number.

20021765 is a deficient number, since it is larger than the sum of its proper divisors (4515835).

20021765 is an equidigital number, since it uses as much as digits as its factorization.

20021765 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 85251.

The product of its (nonzero) digits is 840, while the sum is 23.

The square root of 20021765 is about 4474.5686942989. The cubic root of 20021765 is about 271.5401914618.

Adding to 20021765 its reverse (56712002), we get a palindrome (76733767).

The spelling of 20021765 in words is "twenty million, twenty-one thousand, seven hundred sixty-five".