21543537 has 8 divisors (see below), whose sum is σ = 29088640. Its totient is φ = 14180400.

The previous prime is 21543527. The next prime is 21543551. The reversal of 21543537 is 73534512.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 21543537 - 2¹⁹ = 21019249 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21543527) 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, 45214 + ... + 45687.

It is an arithmetic number, because the mean of its divisors is an integer number (3636080).

Almost surely, 2^21543537 is an apocalyptic number.

It is an amenable number.

21543537 is a deficient number, since it is larger than the sum of its proper divisors (7545103).

21543537 is an equidigital number, since it uses as much as digits as its factorization.

21543537 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 90983.

The product of its digits is 12600, while the sum is 30.

The square root of 21543537 is about 4641.5015889257. The cubic root of 21543537 is about 278.2524534221.

The spelling of 21543537 in words is "twenty-one million, five hundred forty-three thousand, five hundred thirty-seven".