21061949 has 2 divisors, whose sum is σ = 21061950. Its totient is φ = 21061948.

The previous prime is 21061907. The next prime is 21061973. The reversal of 21061949 is 94916012.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 20025625 + 1036324 = 4475^2 + 1018^2 .

It is a cyclic number.

It is not a de Polignac number, because 21061949 - 2⁸ = 21061693 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21061979) 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 as a sum of consecutive naturals, namely, 10530974 + 10530975.

It is an arithmetic number, because the mean of its divisors is an integer number (10530975).

Almost surely, 2^21061949 is an apocalyptic number.

It is an amenable number.

21061949 is a deficient number, since it is larger than the sum of its proper divisors (1).

21061949 is an equidigital number, since it uses as much as digits as its factorization.

21061949 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 3888, while the sum is 32.

The square root of 21061949 is about 4589.3299075137. The cubic root of 21061949 is about 276.1634411418.

The spelling of 21061949 in words is "twenty-one million, sixty-one thousand, nine hundred forty-nine".