21690533 has 16 divisors (see below), whose sum is σ = 23654400. Its totient is φ = 19822320.

The previous prime is 21690527. The next prime is 21690553. The reversal of 21690533 is 33509612.

It is not a de Polignac number, because 21690533 - 2⁶ = 21690469 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21690496 and 21690505.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21690523) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 113468 + ... + 113658.

It is an arithmetic number, because the mean of its divisors is an integer number (1478400).

Almost surely, 2^21690533 is an apocalyptic number.

It is an amenable number.

21690533 is a deficient number, since it is larger than the sum of its proper divisors (1963867).

21690533 is a wasteful number, since it uses less digits than its factorization.

21690533 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 392.

The product of its (nonzero) digits is 4860, while the sum is 29.

The square root of 21690533 is about 4657.3096311068. The cubic root of 21690533 is about 278.8838774557.

The spelling of 21690533 in words is "twenty-one million, six hundred ninety thousand, five hundred thirty-three".