21321036 has 96 divisors (see below), whose sum is σ = 61205760. Its totient is φ = 6364800.

The previous prime is 21321031. The next prime is 21321067. The reversal of 21321036 is 63012312.

21321036 = T₄₈₈ + T₄₈₉ + ... + T₆₂₄.

It is a super-2 number, since 2×21321036² = 909173152226592, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (18).

It is not an unprimeable number, because it can be changed into a prime (21321031) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 155560 + ... + 155696.

It is an arithmetic number, because the mean of its divisors is an integer number (637560).

Almost surely, 2^21321036 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 21321036, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (30602880).

21321036 is an abundant number, since it is smaller than the sum of its proper divisors (39884724).

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

21321036 is a wasteful number, since it uses less digits than its factorization.

21321036 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 292 (or 284 counting only the distinct ones).

The product of its (nonzero) digits is 216, while the sum is 18.

The square root of 21321036 is about 4617.4707362365. The cubic root of 21321036 is about 277.2912089055.

Adding to 21321036 its reverse (63012312), we get a palindrome (84333348).

The spelling of 21321036 in words is "twenty-one million, three hundred twenty-one thousand, thirty-six".