21214540 has 24 divisors (see below), whose sum is σ = 45988992. Its totient is φ = 8211840.

The previous prime is 21214517. The next prime is 21214541. The reversal of 21214540 is 4541212.

It is not an unprimeable number, because it can be changed into a prime (21214541) 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, 16489 + ... + 17728.

It is an arithmetic number, because the mean of its divisors is an integer number (1916208).

Almost surely, 2^21214540 is an apocalyptic number.

21214540 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21214540 is an abundant number, since it is smaller than the sum of its proper divisors (24774452).

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

21214540 is a wasteful number, since it uses less digits than its factorization.

21214540 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 34257 (or 34255 counting only the distinct ones).

The product of its (nonzero) digits is 320, while the sum is 19.

The square root of 21214540 is about 4605.9244457546. The cubic root of 21214540 is about 276.8287593883.

Adding to 21214540 its reverse (4541212), we get a palindrome (25755752).

The spelling of 21214540 in words is "twenty-one million, two hundred fourteen thousand, five hundred forty".