21081357705 has 16 divisors (see below), whose sum is σ = 35714300544. Its totient is φ = 10582014720.

The previous prime is 21081357697. The next prime is 21081357709. The reversal of 21081357705 is 50775318012.

It is not a de Polignac number, because 21081357705 - 2³ = 21081357697 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21081357709) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 41335741 + ... + 41336250.

It is an arithmetic number, because the mean of its divisors is an integer number (2232143784).

Almost surely, 2^21081357705 is an apocalyptic number.

It is an amenable number.

21081357705 is a deficient number, since it is larger than the sum of its proper divisors (14632942839).

21081357705 is a wasteful number, since it uses less digits than its factorization.

21081357705 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 82672016.

The product of its (nonzero) digits is 58800, while the sum is 39.

The spelling of 21081357705 in words is "twenty-one billion, eighty-one million, three hundred fifty-seven thousand, seven hundred five".