21107953 has 2 divisors, whose sum is σ = 21107954. Its totient is φ = 21107952.

The previous prime is 21107929. The next prime is 21107981. The reversal of 21107953 is 35970112.

It is an a-pointer prime, because the next prime (21107981) can be obtained adding 21107953 to its sum of digits (28).

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 15618304 + 5489649 = 3952^2 + 2343^2 .

It is a cyclic number.

It is not a de Polignac number, because 21107953 - 2⁵ = 21107921 is a prime.

It is equal to p_1336366 and since 21107953 and 1336366 have the same sum of digits, it is a Honaker prime.

It is not a weakly prime, because it can be changed into another prime (21107923) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10553976 + 10553977.

It is an arithmetic number, because the mean of its divisors is an integer number (10553977).

Almost surely, 2^21107953 is an apocalyptic number.

It is an amenable number.

21107953 is a deficient number, since it is larger than the sum of its proper divisors (1).

21107953 is an equidigital number, since it uses as much as digits as its factorization.

21107953 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1890, while the sum is 28.

The square root of 21107953 is about 4594.3392343187. The cubic root of 21107953 is about 276.3643624691.

The spelling of 21107953 in words is "twenty-one million, one hundred seven thousand, nine hundred fifty-three".