21475836 has 72 divisors (see below), whose sum is σ = 58260384. Its totient is φ = 6652800.

The previous prime is 21475819. The next prime is 21475837. The reversal of 21475836 is 63857412.

It is a super-2 number, since 2×21475836² = 922423063797792, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a self number, because there is not a number n which added to its sum of digits gives 21475836.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21475837) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 30286 + ... + 30986.

It is an arithmetic number, because the mean of its divisors is an integer number (809172).

Almost surely, 2^21475836 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21475836, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (29130192).

21475836 is an abundant number, since it is smaller than the sum of its proper divisors (36784548).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21475836 is a wasteful number, since it uses less digits than its factorization.

21475836 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 771 (or 766 counting only the distinct ones).

The product of its digits is 40320, while the sum is 36.

The square root of 21475836 is about 4634.2028440715. The cubic root of 21475836 is about 277.9606762521.

The spelling of 21475836 in words is "twenty-one million, four hundred seventy-five thousand, eight hundred thirty-six".