21421036 has 48 divisors (see below), whose sum is σ = 47118400. Its totient is φ = 8467200.

The previous prime is 21420991. The next prime is 21421051. The reversal of 21421036 is 63012412.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 17236 + ... + 18436.

Almost surely, 2^21421036 is an apocalyptic number.

21421036 is a gapful number since it is divisible by the number (26) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21421036, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (23559200).

21421036 is an abundant number, since it is smaller than the sum of its proper divisors (25697364).

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

21421036 is a wasteful number, since it uses less digits than its factorization.

21421036 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1239 (or 1223 counting only the distinct ones).

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

The square root of 21421036 is about 4628.2865079854. The cubic root of 21421036 is about 277.7240503139.

Adding to 21421036 its reverse (63012412), we get a palindrome (84433448).

The spelling of 21421036 in words is "twenty-one million, four hundred twenty-one thousand, thirty-six".