21085461953 has 2 divisors, whose sum is σ = 21085461954. Its totient is φ = 21085461952.

The previous prime is 21085461871. The next prime is 21085461979. The reversal of 21085461953 is 35916458012.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 17724129424 + 3361332529 = 133132^2 + 57977^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21085461953 is a prime.

It is not a weakly prime, because it can be changed into another prime (21085461253) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10542730976 + 10542730977.

It is an arithmetic number, because the mean of its divisors is an integer number (10542730977).

Almost surely, 2^21085461953 is an apocalyptic number.

It is an amenable number.

21085461953 is a deficient number, since it is larger than the sum of its proper divisors (1).

21085461953 is an equidigital number, since it uses as much as digits as its factorization.

21085461953 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 259200, while the sum is 44.

The spelling of 21085461953 in words is "twenty-one billion, eighty-five million, four hundred sixty-one thousand, nine hundred fifty-three".