21271270816 has 12 divisors (see below), whose sum is σ = 41877814482. Its totient is φ = 10635635392.

The previous prime is 21271270799. The next prime is 21271270817. The reversal of 21271270816 is 61807217212.

It can be written as a sum of positive squares in only one way, i.e., 11576899216 + 9694371600 = 107596^2 + 98460^2 .

It is a super-2 number, since 2×21271270816² (a number of 21 digits) contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (21271270817) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 332363575 + ... + 332363638.

Almost surely, 2^21271270816 is an apocalyptic number.

It is an amenable number.

21271270816 is a deficient number, since it is larger than the sum of its proper divisors (20606543666).

21271270816 is an equidigital number, since it uses as much as digits as its factorization.

21271270816 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 664727223 (or 664727215 counting only the distinct ones).

The product of its (nonzero) digits is 18816, while the sum is 37.

The spelling of 21271270816 in words is "twenty-one billion, two hundred seventy-one million, two hundred seventy thousand, eight hundred sixteen".