21335212565 has 32 divisors (see below), whose sum is σ = 26802074880. Its totient is φ = 16282957824.

The previous prime is 21335212559. The next prime is 21335212567. The reversal of 21335212565 is 56521253312.

It is a cyclic number.

It is not a de Polignac number, because 21335212565 - 2¹⁸ = 21334950421 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21335212567) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 14950382 + ... + 14951808.

It is an arithmetic number, because the mean of its divisors is an integer number (837564840).

Almost surely, 2^21335212565 is an apocalyptic number.

It is an amenable number.

21335212565 is a deficient number, since it is larger than the sum of its proper divisors (5466862315).

21335212565 is a wasteful number, since it uses less digits than its factorization.

21335212565 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2621.

The product of its digits is 54000, while the sum is 35.

Adding to 21335212565 its reverse (56521253312), we get a palindrome (77856465877).

The spelling of 21335212565 in words is "twenty-one billion, three hundred thirty-five million, two hundred twelve thousand, five hundred sixty-five".