21987914 has 12 divisors (see below), whose sum is σ = 35714646. Its totient is φ = 10148112.

The previous prime is 21987913. The next prime is 21987923. The reversal of 21987914 is 41978912.

It can be written as a sum of positive squares in 3 ways, for example, as 4906225 + 17081689 = 2215^2 + 4133^2 .

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (21987913) 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 5 ways as a sum of consecutive naturals, for example, 32189 + ... + 32864.

Almost surely, 2^21987914 is an apocalyptic number.

21987914 is a deficient number, since it is larger than the sum of its proper divisors (13726732).

21987914 is a wasteful number, since it uses less digits than its factorization.

21987914 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 65081 (or 65068 counting only the distinct ones).

The product of its digits is 36288, while the sum is 41.

The square root of 21987914 is about 4689.1272108997. The cubic root of 21987914 is about 280.1526123826.

The spelling of 21987914 in words is "twenty-one million, nine hundred eighty-seven thousand, nine hundred fourteen".