21540116 has 24 divisors (see below), whose sum is σ = 40735464. Its totient is φ = 9907200.

The previous prime is 21540083. The next prime is 21540157. The reversal of 21540116 is 61104512.

It can be written as a sum of positive squares in 4 ways, for example, as 11930116 + 9610000 = 3454^2 + 3100^2 .

It is a Smith number, since the sum of its digits (20) coincides with the sum of the digits of its prime factors.

It is a congruent number.

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, 20336 + ... + 21368.

It is an arithmetic number, because the mean of its divisors is an integer number (1697311).

Almost surely, 2^21540116 is an apocalyptic number.

21540116 is a gapful number since it is divisible by the number (26) formed by its first and last digit.

It is an amenable number.

21540116 is a deficient number, since it is larger than the sum of its proper divisors (19195348).

21540116 is a wasteful number, since it uses less digits than its factorization.

21540116 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1451 (or 1449 counting only the distinct ones).

The product of its (nonzero) digits is 240, while the sum is 20.

The square root of 21540116 is about 4641.1330513141. The cubic root of 21540116 is about 278.2377243019.

Adding to 21540116 its reverse (61104512), we get a palindrome (82644628).

The spelling of 21540116 in words is "twenty-one million, five hundred forty thousand, one hundred sixteen".