20521220 has 12 divisors (see below), whose sum is σ = 43094604. Its totient is φ = 8208480.

The previous prime is 20521217. The next prime is 20521253. The reversal of 20521220 is 2212502.

It can be written as a sum of positive squares in 2 ways, for example, as 12859396 + 7661824 = 3586^2 + 2768^2 .

It is a super-2 number, since 2×20521220² = 842240940576800, which contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 20521195 and 20521204.

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, 513011 + ... + 513050.

It is an arithmetic number, because the mean of its divisors is an integer number (3591217).

Almost surely, 2^20521220 is an apocalyptic number.

20521220 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

20521220 is an abundant number, since it is smaller than the sum of its proper divisors (22573384).

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

20521220 is a wasteful number, since it uses less digits than its factorization.

20521220 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1026070 (or 1026068 counting only the distinct ones).

The product of its (nonzero) digits is 80, while the sum is 14.

The square root of 20521220 is about 4530.0353199506. The cubic root of 20521220 is about 273.7795836894.

Adding to 20521220 its reverse (2212502), we get a palindrome (22733722).

The spelling of 20521220 in words is "twenty million, five hundred twenty-one thousand, two hundred twenty".