21672072 has 72 divisors (see below), whose sum is σ = 61465950. Its totient is φ = 6897792.

The previous prime is 21672061. The next prime is 21672073. The reversal of 21672072 is 27027612.

It can be written as a sum of positive squares in only one way, i.e., 20738916 + 933156 = 4554^2 + 966^2 .

It is a tau number, because it is divible by the number of its divisors (72).

It is not an unprimeable number, because it can be changed into a prime (21672073) by changing a digit.

It is a polite number, since it can be written in 17 ways as a sum of consecutive naturals, for example, 37804 + ... + 38372.

Almost surely, 2^21672072 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 21672072, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (30732975).

21672072 is an abundant number, since it is smaller than the sum of its proper divisors (39793878).

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

21672072 is a wasteful number, since it uses less digits than its factorization.

21672072 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 627 (or 597 counting only the distinct ones).

The product of its (nonzero) digits is 2352, while the sum is 27.

The square root of 21672072 is about 4655.3272709875. The cubic root of 21672072 is about 278.8047348394.

Adding to 21672072 its reverse (27027612), we get a palindrome (48699684).

The spelling of 21672072 in words is "twenty-one million, six hundred seventy-two thousand, seventy-two".