21487543 has 24 divisors (see below), whose sum is σ = 28191744. Its totient is φ = 16001040.

The previous prime is 21487519. The next prime is 21487547. The reversal of 21487543 is 34578412.

It is not a de Polignac number, because 21487543 - 2²¹ = 19390391 is a prime.

It is a super-3 number, since 3×21487543³ (a number of 23 digits) contains 333 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 21487499 and 21487508.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21487547) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 18930 + ... + 20032.

It is an arithmetic number, because the mean of its divisors is an integer number (1174656).

Almost surely, 2^21487543 is an apocalyptic number.

21487543 is a gapful number since it is divisible by the number (23) formed by its first and last digit.

21487543 is a deficient number, since it is larger than the sum of its proper divisors (6704201).

21487543 is a wasteful number, since it uses less digits than its factorization.

21487543 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1155 (or 1144 counting only the distinct ones).

The product of its digits is 26880, while the sum is 34.

The square root of 21487543 is about 4635.4657802642. The cubic root of 21487543 is about 278.0111747833.

The spelling of 21487543 in words is "twenty-one million, four hundred eighty-seven thousand, five hundred forty-three".