21210436 has 12 divisors (see below), whose sum is σ = 39973612. Its totient is φ = 9789408.

The previous prime is 21210433. The next prime is 21210461. The reversal of 21210436 is 63401212.

It can be written as a sum of positive squares in 2 ways, for example, as 5953600 + 15256836 = 2440^2 + 3906^2 .

It is not an unprimeable number, because it can be changed into a prime (21210433) 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, 203895 + ... + 203998.

Almost surely, 2^21210436 is an apocalyptic number.

21210436 is a gapful number since it is divisible by the number (26) formed by its first and last digit.

It is an amenable number.

21210436 is a deficient number, since it is larger than the sum of its proper divisors (18763176).

21210436 is a wasteful number, since it uses less digits than its factorization.

21210436 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 407910 (or 407908 counting only the distinct ones).

The product of its (nonzero) digits is 288, while the sum is 19.

The square root of 21210436 is about 4605.4789110363. The cubic root of 21210436 is about 276.8109071905.

Adding to 21210436 its reverse (63401212), we get a palindrome (84611648).

It can be divided in two parts, 212 and 10436, that added together give a cube (10648 = 22³).

The spelling of 21210436 in words is "twenty-one million, two hundred ten thousand, four hundred thirty-six".