21488540 has 12 divisors (see below), whose sum is σ = 45125976. Its totient is φ = 8595408.

The previous prime is 21488539. The next prime is 21488543. The reversal of 21488540 is 4588412.

It is a happy number.

It is a hoax number, since the sum of its digits (32) coincides with the sum of the digits of its distinct prime factors.

It is a junction number, because it is equal to n+sod(n) for n = 21488497 and 21488506.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21488543) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 537194 + ... + 537233.

It is an arithmetic number, because the mean of its divisors is an integer number (3760498).

Almost surely, 2^21488540 is an apocalyptic number.

21488540 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21488540 is an abundant number, since it is smaller than the sum of its proper divisors (23637436).

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

21488540 is a wasteful number, since it uses less digits than its factorization.

21488540 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1074436 (or 1074434 counting only the distinct ones).

The product of its (nonzero) digits is 10240, while the sum is 32.

The square root of 21488540 is about 4635.5733194504. The cubic root of 21488540 is about 278.0154745281.

The spelling of 21488540 in words is "twenty-one million, four hundred eighty-eight thousand, five hundred forty".