21336805 has 24 divisors (see below), whose sum is σ = 30217752. Its totient is φ = 14418432.

The previous prime is 21336803. The next prime is 21336839. The reversal of 21336805 is 50863312.

21336805 = T₁₄ + T₁₅ + ... + T₅₀₃.

It can be written as a sum of positive squares in 4 ways, for example, as 2683044 + 18653761 = 1638^2 + 4319^2 .

It is not a de Polignac number, because 21336805 - 2¹ = 21336803 is a prime.

It is a super-3 number, since 3×21336805³ (a number of 23 digits) contains 333 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21336803) 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, 17289 + ... + 18481.

It is an arithmetic number, because the mean of its divisors is an integer number (1259073).

Almost surely, 2^21336805 is an apocalyptic number.

It is an amenable number.

21336805 is a deficient number, since it is larger than the sum of its proper divisors (8880947).

21336805 is a wasteful number, since it uses less digits than its factorization.

21336805 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1285 (or 1278 counting only the distinct ones).

The product of its (nonzero) digits is 4320, while the sum is 28.

The square root of 21336805 is about 4619.1779571694. The cubic root of 21336805 is about 277.3595534194.

The spelling of 21336805 in words is "twenty-one million, three hundred thirty-six thousand, eight hundred five".