21247541065 has 16 divisors (see below), whose sum is σ = 26930635200. Its totient is φ = 16048418112.

The previous prime is 21247541017. The next prime is 21247541087. The reversal of 21247541065 is 56014574212.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21247541065 is a prime.

It is a super-2 number, since 2×21247541065² (a number of 21 digits) contains 22 as substring.

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, 353835 + ... + 409504.

It is an arithmetic number, because the mean of its divisors is an integer number (1683164700).

Almost surely, 2^21247541065 is an apocalyptic number.

It is an amenable number.

21247541065 is a deficient number, since it is larger than the sum of its proper divisors (5683094135).

21247541065 is a wasteful number, since it uses less digits than its factorization.

21247541065 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 763656.

The product of its (nonzero) digits is 67200, while the sum is 37.

The spelling of 21247541065 in words is "twenty-one billion, two hundred forty-seven million, five hundred forty-one thousand, sixty-five".