21540783 has 12 divisors (see below), whose sum is σ = 31569944. Its totient is φ = 13054800.

The previous prime is 21540773. The next prime is 21540787. The reversal of 21540783 is 38704512.

It is not a de Polignac number, because 21540783 - 2⁹ = 21540271 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21540783.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21540787) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 29308 + ... + 30033.

Almost surely, 2^21540783 is an apocalyptic number.

21540783 is a deficient number, since it is larger than the sum of its proper divisors (10029161).

21540783 is a wasteful number, since it uses less digits than its factorization.

21540783 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 59366 (or 59355 counting only the distinct ones).

The product of its (nonzero) digits is 6720, while the sum is 30.

The square root of 21540783 is about 4641.2049082108. The cubic root of 21540783 is about 278.2405961937.

The spelling of 21540783 in words is "twenty-one million, five hundred forty thousand, seven hundred eighty-three".