21321572 has 12 divisors (see below), whose sum is σ = 39276720. Its totient is φ = 10099656.

The previous prime is 21321563. The next prime is 21321577. The reversal of 21321572 is 27512312.

It is a happy number.

It is not an unprimeable number, because it can be changed into a prime (21321577) 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, 140198 + ... + 140349.

It is an arithmetic number, because the mean of its divisors is an integer number (3273060).

Almost surely, 2^21321572 is an apocalyptic number.

It is an amenable number.

21321572 is a deficient number, since it is larger than the sum of its proper divisors (17955148).

21321572 is a wasteful number, since it uses less digits than its factorization.

21321572 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 280570 (or 280568 counting only the distinct ones).

The product of its digits is 840, while the sum is 23.

The square root of 21321572 is about 4617.5287763045. The cubic root of 21321572 is about 277.2935325393.

Adding to 21321572 its reverse (27512312), we get a palindrome (48833884).

The spelling of 21321572 in words is "twenty-one million, three hundred twenty-one thousand, five hundred seventy-two".