20857490 has 16 divisors (see below), whose sum is σ = 37604952. Its totient is φ = 8329344.

The previous prime is 20857483. The next prime is 20857511. The reversal of 20857490 is 9475802.

It is a happy number.

It is a Cunningham number, because it is equal to 4567²+1.

It can be written as a sum of positive squares in 4 ways, for example, as 20349121 + 508369 = 4511^2 + 713^2 .

It is a self number, because there is not a number n which added to its sum of digits gives 20857490.

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, 6662 + ... + 9278.

Almost surely, 2^20857490 is an apocalyptic number.

20857490 is a deficient number, since it is larger than the sum of its proper divisors (16747462).

20857490 is a wasteful number, since it uses less digits than its factorization.

20857490 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3421.

The product of its (nonzero) digits is 20160, while the sum is 35.

The square root of 20857490 is about 4567.0001094811. Note that the first 3 decimals coincide. The cubic root of 20857490 is about 275.2669144034.

The spelling of 20857490 in words is "twenty million, eight hundred fifty-seven thousand, four hundred ninety".