20213540 has 24 divisors (see below), whose sum is σ = 42597240. Its totient is φ = 8057088.

The previous prime is 20213503. The next prime is 20213563. The reversal of 20213540 is 4531202.

It can be written as a sum of positive squares in 4 ways, for example, as 357604 + 19855936 = 598^2 + 4456^2 .

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 4646 + ... + 7874.

It is an arithmetic number, because the mean of its divisors is an integer number (1774885).

Almost surely, 2^20213540 is an apocalyptic number.

20213540 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

20213540 is an abundant number, since it is smaller than the sum of its proper divisors (22383700).

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

20213540 is a wasteful number, since it uses less digits than its factorization.

20213540 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3551 (or 3549 counting only the distinct ones).

The product of its (nonzero) digits is 240, while the sum is 17.

The square root of 20213540 is about 4495.9470637453. The cubic root of 20213540 is about 272.4044049276.

Adding to 20213540 its reverse (4531202), we get a palindrome (24744742).

The spelling of 20213540 in words is "twenty million, two hundred thirteen thousand, five hundred forty".