21065105571 has 8 divisors (see below), whose sum is σ = 28307963904. Its totient is φ = 13932825480.

The previous prime is 21065105543. The next prime is 21065105591. The reversal of 21065105571 is 17550156012.

It is a happy number.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 21065105571 - 2¹¹ = 21065103523 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21065105591) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 27644115 + ... + 27644876.

It is an arithmetic number, because the mean of its divisors is an integer number (3538495488).

Almost surely, 2^21065105571 is an apocalyptic number.

21065105571 is a deficient number, since it is larger than the sum of its proper divisors (7242858333).

21065105571 is a wasteful number, since it uses less digits than its factorization.

21065105571 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 55289121.

The product of its (nonzero) digits is 10500, while the sum is 33.

The spelling of 21065105571 in words is "twenty-one billion, sixty-five million, one hundred five thousand, five hundred seventy-one".