20828405 has 18 divisors (see below), whose sum is σ = 27238086. Its totient is φ = 15283008.

The previous prime is 20828399. The next prime is 20828411. The reversal of 20828405 is 50482802.

It is an interprime number because it is at equal distance from previous prime (20828399) and next prime (20828411).

It can be written as a sum of positive squares in 9 ways, for example, as 15984004 + 4844401 = 3998^2 + 2201^2 .

It is not a de Polignac number, because 20828405 - 2⁸ = 20828149 is a prime.

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 17 ways as a sum of consecutive naturals, for example, 132587 + ... + 132743.

It is an arithmetic number, because the mean of its divisors is an integer number (1513227).

Almost surely, 2^20828405 is an apocalyptic number.

It is an amenable number.

20828405 is a deficient number, since it is larger than the sum of its proper divisors (6409681).

20828405 is an equidigital number, since it uses as much as digits as its factorization.

20828405 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 345 (or 175 counting only the distinct ones).

The product of its (nonzero) digits is 5120, while the sum is 29.

The square root of 20828405 is about 4563.8147420771. The cubic root of 20828405 is about 275.1389050326.

Multiplying 20828405 by its product of nonzero digits (5120), we get a square (106641433600 = 326560²).

The spelling of 20828405 in words is "twenty million, eight hundred twenty-eight thousand, four hundred five".