21981107 has 2 divisors, whose sum is σ = 21981108. Its totient is φ = 21981106.

The previous prime is 21981079. The next prime is 21981121. The reversal of 21981107 is 70118912.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21981107 - 2⁸ = 21980851 is a prime.

It is a Chen prime.

It is equal to p_1388135 and since 21981107 and 1388135 have the same sum of digits, it is a Honaker prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21981107.

It is not a weakly prime, because it can be changed into another prime (21981137) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10990553 + 10990554.

It is an arithmetic number, because the mean of its divisors is an integer number (10990554).

Almost surely, 2^21981107 is an apocalyptic number.

21981107 is a deficient number, since it is larger than the sum of its proper divisors (1).

21981107 is an equidigital number, since it uses as much as digits as its factorization.

21981107 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1008, while the sum is 29.

The square root of 21981107 is about 4688.4013266784. The cubic root of 21981107 is about 280.1236995951.

The spelling of 21981107 in words is "twenty-one million, nine hundred eighty-one thousand, one hundred seven".