21520853 has 2 divisors, whose sum is σ = 21520854. Its totient is φ = 21520852.

The previous prime is 21520843. The next prime is 21520867. The reversal of 21520853 is 35802512.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 20133169 + 1387684 = 4487^2 + 1178^2 .

It is a cyclic number.

It is not a de Polignac number, because 21520853 - 2²⁴ = 4743637 is a prime.

It is a super-2 number, since 2×21520853² = 926294227695218, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21520843) 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, 10760426 + 10760427.

It is an arithmetic number, because the mean of its divisors is an integer number (10760427).

Almost surely, 2^21520853 is an apocalyptic number.

It is an amenable number.

21520853 is a deficient number, since it is larger than the sum of its proper divisors (1).

21520853 is an equidigital number, since it uses as much as digits as its factorization.

21520853 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 2400, while the sum is 26.

The square root of 21520853 is about 4639.0573395896. The cubic root of 21520853 is about 278.1547583022.

The spelling of 21520853 in words is "twenty-one million, five hundred twenty thousand, eight hundred fifty-three".