21572747066 has 16 divisors (see below), whose sum is σ = 35790130824. Its totient is φ = 9687553344.

The previous prime is 21572747017. The next prime is 21572747071. The reversal of 21572747066 is 66074727512.

It can be written as a sum of positive squares in 4 ways, for example, as 21236941441 + 335805625 = 145729^2 + 18325^2 .

It is a super-2 number, since 2×21572747066² (a number of 21 digits) contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 21572747066.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 11211485 + ... + 11213408.

Almost surely, 2^21572747066 is an apocalyptic number.

21572747066 is a gapful number since it is divisible by the number (26) formed by its first and last digit.

21572747066 is a deficient number, since it is larger than the sum of its proper divisors (14217383758).

21572747066 is a wasteful number, since it uses less digits than its factorization.

21572747066 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 22424945.

The product of its (nonzero) digits is 987840, while the sum is 47.

The spelling of 21572747066 in words is "twenty-one billion, five hundred seventy-two million, seven hundred forty-seven thousand, sixty-six".