21171572 has 12 divisors (see below), whose sum is σ = 37128000. Its totient is φ = 10563576.

The previous prime is 21171571. The next prime is 21171593. The reversal of 21171572 is 27517112.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21171571) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3308 + ... + 7299.

It is an arithmetic number, because the mean of its divisors is an integer number (3094000).

Almost surely, 2^21171572 is an apocalyptic number.

It is an amenable number.

21171572 is a deficient number, since it is larger than the sum of its proper divisors (15956428).

21171572 is a wasteful number, since it uses less digits than its factorization.

21171572 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 11110 (or 11108 counting only the distinct ones).

The product of its digits is 980, while the sum is 26.

The square root of 21171572 is about 4601.2576541637. The cubic root of 21171572 is about 276.6417364353.

Adding to 21171572 its reverse (27517112), we get a palindrome (48688684).

The spelling of 21171572 in words is "twenty-one million, one hundred seventy-one thousand, five hundred seventy-two".