21645717101705 has 16 divisors (see below), whose sum is σ = 26143689697104. Its totient is φ = 17204049457920.

The previous prime is 21645717101689. The next prime is 21645717101753. The reversal of 21645717101705 is 50710171754612.

It can be written as a sum of positive squares in 8 ways, for example, as 9376872860224 + 12268844241481 = 3062168^2 + 3502691^2 .

It is not a de Polignac number, because 21645717101705 - 2⁴ = 21645717101689 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21645717101705.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 4295639 + ... + 7857731.

It is an arithmetic number, because the mean of its divisors is an integer number (1633980606069).

Almost surely, 2^{21645717101705} is an apocalyptic number.

It is an amenable number.

21645717101705 is a deficient number, since it is larger than the sum of its proper divisors (4497972595399).

21645717101705 is a wasteful number, since it uses less digits than its factorization.

21645717101705 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3569996.

The product of its (nonzero) digits is 411600, while the sum is 47.

The spelling of 21645717101705 in words is "twenty-one trillion, six hundred forty-five billion, seven hundred seventeen million, one hundred one thousand, seven hundred five".