21072132 has 18 divisors (see below), whose sum is σ = 53265758. Its totient is φ = 7024032.

The previous prime is 21072131. The next prime is 21072133. The reversal of 21072132 is 23127012.

It is an interprime number because it is at equal distance from previous prime (21072131) and next prime (21072133).

It can be written as a sum of positive squares in only one way, i.e., 20196036 + 876096 = 4494^2 + 936^2 .

It is a tau number, because it is divible by the number of its divisors (18).

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 (21072131) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 292633 + ... + 292704.

Almost surely, 2^21072132 is an apocalyptic number.

It is an amenable number.

21072132 is an abundant number, since it is smaller than the sum of its proper divisors (32193626).

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

21072132 is a wasteful number, since it uses less digits than its factorization.

21072132 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 585347 (or 585342 counting only the distinct ones).

The product of its (nonzero) digits is 168, while the sum is 18.

The square root of 21072132 is about 4590.4391946741. The cubic root of 21072132 is about 276.2079403354.

Adding to 21072132 its reverse (23127012), we get a palindrome (44199144).

The spelling of 21072132 in words is "twenty-one million, seventy-two thousand, one hundred thirty-two".