21336540 has 24 divisors (see below), whose sum is σ = 59742480. Its totient is φ = 5689728.

The previous prime is 21336529. The next prime is 21336541. The reversal of 21336540 is 4563312.

It is a happy number.

It is a self number, because there is not a number n which added to its sum of digits gives 21336540.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21336541) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 177745 + ... + 177864.

It is an arithmetic number, because the mean of its divisors is an integer number (2489270).

Almost surely, 2^21336540 is an apocalyptic number.

21336540 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21336540 is an abundant number, since it is smaller than the sum of its proper divisors (38405940).

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

21336540 is a wasteful number, since it uses less digits than its factorization.

21336540 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 355621 (or 355619 counting only the distinct ones).

The product of its (nonzero) digits is 2160, while the sum is 24.

The square root of 21336540 is about 4619.1492723228. The cubic root of 21336540 is about 277.3584051596.

Adding to 21336540 its reverse (4563312), we get a palindrome (25899852).

The spelling of 21336540 in words is "twenty-one million, three hundred thirty-six thousand, five hundred forty".