21165072 has 20 divisors (see below), whose sum is σ = 54676560. Its totient is φ = 7055008.

The previous prime is 21165047. The next prime is 21165077. The reversal of 21165072 is 27056112.

It is a super-3 number, since 3×21165072³ (a number of 23 digits) contains 333 as substring.

It is a Harshad number since it is a multiple of its sum of digits (24).

It is not an unprimeable number, because it can be changed into a prime (21165077) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 220422 + ... + 220517.

It is an arithmetic number, because the mean of its divisors is an integer number (2733828).

Almost surely, 2^21165072 is an apocalyptic number.

It is an amenable number.

21165072 is an abundant number, since it is smaller than the sum of its proper divisors (33511488).

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

21165072 is a wasteful number, since it uses less digits than its factorization.

21165072 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 440950 (or 440944 counting only the distinct ones).

The product of its (nonzero) digits is 840, while the sum is 24.

The square root of 21165072 is about 4600.5512713152. The cubic root of 21165072 is about 276.6134224404.

The spelling of 21165072 in words is "twenty-one million, one hundred sixty-five thousand, seventy-two".