21635140 has 12 divisors (see below), whose sum is σ = 45433836. Its totient is φ = 8654048.

The previous prime is 21635137. The next prime is 21635197. The reversal of 21635140 is 4153612.

It can be written as a sum of positive squares in 2 ways, for example, as 10771524 + 10863616 = 3282^2 + 3296^2 .

It is a plaindrome in base 11.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 540859 + ... + 540898.

It is an arithmetic number, because the mean of its divisors is an integer number (3786153).

Almost surely, 2^21635140 is an apocalyptic number.

21635140 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21635140 is an abundant number, since it is smaller than the sum of its proper divisors (23798696).

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

21635140 is a wasteful number, since it uses less digits than its factorization.

21635140 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1081766 (or 1081764 counting only the distinct ones).

The product of its (nonzero) digits is 720, while the sum is 22.

The square root of 21635140 is about 4651.3589412128. The cubic root of 21635140 is about 278.6462717409.

Adding to 21635140 its reverse (4153612), we get a palindrome (25788752).

The spelling of 21635140 in words is "twenty-one million, six hundred thirty-five thousand, one hundred forty".