21260813668 has 6 divisors (see below), whose sum is σ = 37206423926. Its totient is φ = 10630406832.

The previous prime is 21260813627. The next prime is 21260813689. The reversal of 21260813668 is 86631806212.

It can be written as a sum of positive squares in only one way, i.e., 15540614244 + 5720199424 = 124662^2 + 75632^2 .

It is a super-2 number, since 2×21260813668² (a number of 21 digits) contains 22 as substring.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 2657601705 + ... + 2657601712.

Almost surely, 2^21260813668 is an apocalyptic number.

It is an amenable number.

21260813668 is a deficient number, since it is larger than the sum of its proper divisors (15945610258).

21260813668 is a wasteful number, since it uses less digits than its factorization.

21260813668 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5315203421 (or 5315203419 counting only the distinct ones).

The product of its (nonzero) digits is 165888, while the sum is 43.

The spelling of 21260813668 in words is "twenty-one billion, two hundred sixty million, eight hundred thirteen thousand, six hundred sixty-eight".