21053969 has 2 divisors, whose sum is σ = 21053970. Its totient is φ = 21053968.

The previous prime is 21053941. The next prime is 21053983. The reversal of 21053969 is 96935012.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 21049744 + 4225 = 4588^2 + 65^2 .

It is a cyclic number.

It is not a de Polignac number, because 21053969 - 2⁸ = 21053713 is a prime.

It is a super-2 number, since 2×21053969² = 886539221305922, which contains 22 as substring.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (21053909) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10526984 + 10526985.

It is an arithmetic number, because the mean of its divisors is an integer number (10526985).

Almost surely, 2^21053969 is an apocalyptic number.

It is an amenable number.

21053969 is a deficient number, since it is larger than the sum of its proper divisors (1).

21053969 is an equidigital number, since it uses as much as digits as its factorization.

21053969 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 14580, while the sum is 35.

The square root of 21053969 is about 4588.4604171770. The cubic root of 21053969 is about 276.1285589214.

It can be divided in two parts, 21053 and 969, that added together give a palindrome (22022).

The spelling of 21053969 in words is "twenty-one million, fifty-three thousand, nine hundred sixty-nine".