21689433 has 12 divisors (see below), whose sum is σ = 33172308. Its totient is φ = 13608960.

The previous prime is 21689413. The next prime is 21689449. The reversal of 21689433 is 33498612.

21689433 is a `hidden beast` number, since 216 + 8 + 9 + 433 = 666.

It can be written as a sum of positive squares in 2 ways, for example, as 10419984 + 11269449 = 3228^2 + 3357^2 .

It is not a de Polignac number, because 21689433 - 2⁸ = 21689177 is a prime.

It is a super-2 number, since 2×21689433² = 940863007722978, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21689413) 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 11 ways as a sum of consecutive naturals, for example, 70728 + ... + 71033.

It is an arithmetic number, because the mean of its divisors is an integer number (2764359).

Almost surely, 2^21689433 is an apocalyptic number.

It is an amenable number.

21689433 is a deficient number, since it is larger than the sum of its proper divisors (11482875).

21689433 is a wasteful number, since it uses less digits than its factorization.

21689433 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 141784 (or 141781 counting only the distinct ones).

The product of its digits is 31104, while the sum is 36.

The square root of 21689433 is about 4657.1915356790. The cubic root of 21689433 is about 278.8791629957.

It can be divided in two parts, 21689 and 433, that added together give a palindrome (22122).

The spelling of 21689433 in words is "twenty-one million, six hundred eighty-nine thousand, four hundred thirty-three".