21981412 has 12 divisors (see below), whose sum is σ = 39405996. Its totient is φ = 10722560.

The previous prime is 21981403. The next prime is 21981419. The reversal of 21981412 is 21418912.

It can be written as a sum of positive squares in 2 ways, for example, as 5788836 + 16192576 = 2406^2 + 4024^2 .

It is not an unprimeable number, because it can be changed into a prime (21981419) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 66853 + ... + 67180.

It is an arithmetic number, because the mean of its divisors is an integer number (3283833).

Almost surely, 2^21981412 is an apocalyptic number.

It is an amenable number.

21981412 is a deficient number, since it is larger than the sum of its proper divisors (17424584).

21981412 is a wasteful number, since it uses less digits than its factorization.

21981412 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 134078 (or 134076 counting only the distinct ones).

The product of its digits is 1152, while the sum is 28.

The square root of 21981412 is about 4688.4338536445. The cubic root of 21981412 is about 280.1249952128.

Subtracting from 21981412 its reverse (21418912), we obtain a square (562500 = 750²).

The spelling of 21981412 in words is "twenty-one million, nine hundred eighty-one thousand, four hundred twelve".