21870533 has 4 divisors (see below), whose sum is σ = 22241280. Its totient is φ = 21499788.

The previous prime is 21870473. The next prime is 21870547. The reversal of 21870533 is 33507812.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 21870533 - 2²² = 17676229 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21870496 and 21870505.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21870733) 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, 185285 + ... + 185402.

It is an arithmetic number, because the mean of its divisors is an integer number (5560320).

Almost surely, 2^21870533 is an apocalyptic number.

It is an amenable number.

21870533 is a deficient number, since it is larger than the sum of its proper divisors (370747).

21870533 is an equidigital number, since it uses as much as digits as its factorization.

21870533 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 370746.

The product of its (nonzero) digits is 5040, while the sum is 29.

The square root of 21870533 is about 4676.5941666987. The cubic root of 21870533 is about 279.6531973348.

The spelling of 21870533 in words is "twenty-one million, eight hundred seventy thousand, five hundred thirty-three".