21085155473 has 2 divisors, whose sum is σ = 21085155474. Its totient is φ = 21085155472.

The previous prime is 21085155457. The next prime is 21085155523. The reversal of 21085155473 is 37455158012.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 11446432144 + 9638723329 = 106988^2 + 98177^2 .

It is a cyclic number.

It is not a de Polignac number, because 21085155473 - 2⁴ = 21085155457 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21085155473.

It is not a weakly prime, because it can be changed into another prime (21085155433) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10542577736 + 10542577737.

It is an arithmetic number, because the mean of its divisors is an integer number (10542577737).

Almost surely, 2^21085155473 is an apocalyptic number.

It is an amenable number.

21085155473 is a deficient number, since it is larger than the sum of its proper divisors (1).

21085155473 is an equidigital number, since it uses as much as digits as its factorization.

21085155473 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 168000, while the sum is 41.

The spelling of 21085155473 in words is "twenty-one billion, eighty-five million, one hundred fifty-five thousand, four hundred seventy-three".