20828861 has 4 divisors (see below), whose sum is σ = 21336924. Its totient is φ = 20320800.

The previous prime is 20828851. The next prime is 20828867. The reversal of 20828861 is 16882802.

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 11256025 + 9572836 = 3355^2 + 3094^2 .

It is a cyclic number.

It is not a de Polignac number, because 20828861 - 2¹⁰ = 20827837 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20828867) 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, 253970 + ... + 254051.

It is an arithmetic number, because the mean of its divisors is an integer number (5334231).

Almost surely, 2^20828861 is an apocalyptic number.

It is an amenable number.

20828861 is a deficient number, since it is larger than the sum of its proper divisors (508063).

20828861 is an equidigital number, since it uses as much as digits as its factorization.

20828861 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 508062.

The product of its (nonzero) digits is 12288, while the sum is 35.

The square root of 20828861 is about 4563.8647000103. The cubic root of 20828861 is about 275.1409129064.

The spelling of 20828861 in words is "twenty million, eight hundred twenty-eight thousand, eight hundred sixty-one".