21085312477 has 2 divisors, whose sum is σ = 21085312478. Its totient is φ = 21085312476.

The previous prime is 21085312463. The next prime is 21085312511. The reversal of 21085312477 is 77421358012.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 18958811481 + 2126500996 = 137691^2 + 46114^2 .

It is a cyclic number.

It is not a de Polignac number, because 21085312477 - 2¹⁹ = 21084788189 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21085312777) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10542656238 + 10542656239.

It is an arithmetic number, because the mean of its divisors is an integer number (10542656239).

Almost surely, 2^21085312477 is an apocalyptic number.

It is an amenable number.

21085312477 is a deficient number, since it is larger than the sum of its proper divisors (1).

21085312477 is an equidigital number, since it uses as much as digits as its factorization.

21085312477 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 94080, while the sum is 40.

The spelling of 21085312477 in words is "twenty-one billion, eighty-five million, three hundred twelve thousand, four hundred seventy-seven".