21012264 has 128 divisors (see below), whose sum is σ = 71904000. Its totient is φ = 5536512.

The previous prime is 21012259. The next prime is 21012281. The reversal of 21012264 is 46221012.

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

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 19122 + ... + 20190.

It is an arithmetic number, because the mean of its divisors is an integer number (561750).

Almost surely, 2^21012264 is an apocalyptic number.

21012264 is a gapful number since it is divisible by the number (24) 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 21012264, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (35952000).

21012264 is an abundant number, since it is smaller than the sum of its proper divisors (50891736).

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

21012264 is a wasteful number, since it uses less digits than its factorization.

21012264 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1104 (or 1094 counting only the distinct ones).

The product of its (nonzero) digits is 192, while the sum is 18.

The square root of 21012264 is about 4583.9136117514. The cubic root of 21012264 is about 275.9461142438.

Adding to 21012264 its reverse (46221012), we get a palindrome (67233276).

The spelling of 21012264 in words is "twenty-one million, twelve thousand, two hundred sixty-four".