20857220 has 12 divisors (see below), whose sum is σ = 43800204. Its totient is φ = 8342880.

The previous prime is 20857217. The next prime is 20857247. The reversal of 20857220 is 2275802.

It can be written as a sum of positive squares in 2 ways, for example, as 4227136 + 16630084 = 2056^2 + 4078^2 .

It is a super-2 number, since 2×20857220² = 870047252256800, which contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 20857220.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 521411 + ... + 521450.

It is an arithmetic number, because the mean of its divisors is an integer number (3650017).

Almost surely, 2^20857220 is an apocalyptic number.

20857220 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

20857220 is an abundant number, since it is smaller than the sum of its proper divisors (22942984).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

20857220 is a wasteful number, since it uses less digits than its factorization.

20857220 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1042870 (or 1042868 counting only the distinct ones).

The product of its (nonzero) digits is 2240, while the sum is 26.

The square root of 20857220 is about 4566.9705495000. The cubic root of 20857220 is about 275.2657266224.

The spelling of 20857220 in words is "twenty million, eight hundred fifty-seven thousand, two hundred twenty".