21221372 has 24 divisors (see below), whose sum is σ = 39463200. Its totient is φ = 9950720.

The previous prime is 21221371. The next prime is 21221377. The reversal of 21221372 is 27312212.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21221371) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 35129 + ... + 35727.

It is an arithmetic number, because the mean of its divisors is an integer number (1644300).

Almost surely, 2^21221372 is an apocalyptic number.

It is an amenable number.

21221372 is a deficient number, since it is larger than the sum of its proper divisors (18241828).

21221372 is a wasteful number, since it uses less digits than its factorization.

21221372 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1141 (or 1139 counting only the distinct ones).

The product of its digits is 336, while the sum is 20.

The square root of 21221372 is about 4606.6660395562. Note that the first 3 decimals coincide. The cubic root of 21221372 is about 276.8584731459.

Adding to 21221372 its reverse (27312212), we get a palindrome (48533584).

The spelling of 21221372 in words is "twenty-one million, two hundred twenty-one thousand, three hundred seventy-two".