21205332 has 36 divisors (see below), whose sum is σ = 54343380. Its totient is φ = 6970752.

The previous prime is 21205313. The next prime is 21205361. The reversal of 21205332 is 23350212.

It can be written as a sum of positive squares in 2 ways, for example, as 4016016 + 17189316 = 2004^2 + 4146^2 .

It is a tau number, because it is divible by the number of its divisors (36).

It is a super-2 number, since 2×21205332² = 899332210460448, which contains 22 as substring.

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

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 1407 + ... + 6662.

Almost surely, 2^21205332 is an apocalyptic number.

It is an amenable number.

21205332 is an abundant number, since it is smaller than the sum of its proper divisors (33138048).

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

21205332 is a wasteful number, since it uses less digits than its factorization.

21205332 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8152 (or 8147 counting only the distinct ones).

The product of its (nonzero) digits is 360, while the sum is 18.

The square root of 21205332 is about 4604.9247550856. The cubic root of 21205332 is about 276.7887018287.

Adding to 21205332 its reverse (23350212), we get a palindrome (44555544).

The spelling of 21205332 in words is "twenty-one million, two hundred five thousand, three hundred thirty-two".