21380672 has 28 divisors (see below), whose sum is σ = 43578780. Its totient is φ = 10400256.

The previous prime is 21380663. The next prime is 21380687. The reversal of 21380672 is 27608312.

It is a happy number.

It can be written as a sum of positive squares in 2 ways, for example, as 20647936 + 732736 = 4544^2 + 856^2 .

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2147 + ... + 6882.

It is an arithmetic number, because the mean of its divisors is an integer number (1556385).

Almost surely, 2^21380672 is an apocalyptic number.

It is an amenable number.

21380672 is an abundant number, since it is smaller than the sum of its proper divisors (22198108).

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

21380672 is an equidigital number, since it uses as much as digits as its factorization.

21380672 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9078 (or 9068 counting only the distinct ones).

The product of its (nonzero) digits is 4032, while the sum is 29.

The square root of 21380672 is about 4623.9238748059. The cubic root of 21380672 is about 277.5495006790.

Adding to 21380672 its reverse (27608312), we get a palindrome (48988984).

The spelling of 21380672 in words is "twenty-one million, three hundred eighty thousand, six hundred seventy-two".