21601245065 has 32 divisors (see below), whose sum is σ = 27624240000. Its totient is φ = 16169338368.

The previous prime is 21601245037. The next prime is 21601245079. The reversal of 21601245065 is 56054210612.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21601245065 is a prime.

It is a super-2 number, since 2×21601245065² (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 31 ways as a sum of consecutive naturals, for example, 3544541 + ... + 3550629.

It is an arithmetic number, because the mean of its divisors is an integer number (863257500).

Almost surely, 2^21601245065 is an apocalyptic number.

It is an amenable number.

21601245065 is a deficient number, since it is larger than the sum of its proper divisors (6022994935).

21601245065 is a wasteful number, since it uses less digits than its factorization.

21601245065 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6569.

The product of its (nonzero) digits is 14400, while the sum is 32.

Adding to 21601245065 its reverse (56054210612), we get a palindrome (77655455677).

The spelling of 21601245065 in words is "twenty-one billion, six hundred one million, two hundred forty-five thousand, sixty-five".