20920985 has 4 divisors (see below), whose sum is σ = 25105188. Its totient is φ = 16736784.

The previous prime is 20920981. The next prime is 20920993. The reversal of 20920985 is 58902902.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 10004569 + 10916416 = 3163^2 + 3304^2 .

It is a cyclic number.

It is not a de Polignac number, because 20920985 - 2² = 20920981 is a prime.

It is a super-2 number, since 2×20920985² = 875375226740450, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20920981) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2092094 + ... + 2092103.

It is an arithmetic number, because the mean of its divisors is an integer number (6276297).

Almost surely, 2^20920985 is an apocalyptic number.

It is an amenable number.

20920985 is a deficient number, since it is larger than the sum of its proper divisors (4184203).

20920985 is an equidigital number, since it uses as much as digits as its factorization.

20920985 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4184202.

The product of its (nonzero) digits is 12960, while the sum is 35.

The square root of 20920985 is about 4573.9463267511. The cubic root of 20920985 is about 275.5459567187.

The spelling of 20920985 in words is "twenty million, nine hundred twenty thousand, nine hundred eighty-five".