21001332 has 48 divisors (see below), whose sum is σ = 53726400. Its totient is φ = 6332160.

The previous prime is 21001319. The next prime is 21001349. The reversal of 21001332 is 23310012.

It is a happy number.

It is a super-3 number, since 3×21001332³ (a number of 23 digits) contains 333 as substring.

It is a Harshad number since it is a multiple of its sum of digits (12).

It is a congruent number.

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, 51144 + ... + 51552.

It is an arithmetic number, because the mean of its divisors is an integer number (1119300).

Almost surely, 2^21001332 is an apocalyptic number.

21001332 is a gapful number since it is divisible by the number (22) formed by its first and last digit.

It is an amenable number.

21001332 is an abundant number, since it is smaller than the sum of its proper divisors (32725068).

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

21001332 is a wasteful number, since it uses less digits than its factorization.

21001332 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 816 (or 814 counting only the distinct ones).

The product of its (nonzero) digits is 36, while the sum is 12.

The square root of 21001332 is about 4582.7210257662. The cubic root of 21001332 is about 275.8982506688.

Adding to 21001332 its reverse (23310012), we get a palindrome (44311344).

The spelling of 21001332 in words is "twenty-one million, one thousand, three hundred thirty-two".