20998765 has 8 divisors (see below), whose sum is σ = 25813368. Its totient is φ = 16389120.

The previous prime is 20998739. The next prime is 20998771. The reversal of 20998765 is 56789902.

It can be written as a sum of positive squares in 4 ways, for example, as 514089 + 20484676 = 717^2 + 4526^2 .

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

It is not a de Polignac number, because 20998765 - 2²¹ = 18901613 is a prime.

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 51012 + ... + 51421.

It is an arithmetic number, because the mean of its divisors is an integer number (3226671).

Almost surely, 2^20998765 is an apocalyptic number.

It is an amenable number.

20998765 is a deficient number, since it is larger than the sum of its proper divisors (4814603).

20998765 is a wasteful number, since it uses less digits than its factorization.

20998765 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 102479.

The product of its (nonzero) digits is 272160, while the sum is 46.

The square root of 20998765 is about 4582.4409434274. The cubic root of 20998765 is about 275.8870091649.

The spelling of 20998765 in words is "twenty million, nine hundred ninety-eight thousand, seven hundred sixty-five".