21203210065 has 16 divisors (see below), whose sum is σ = 26122597200. Its totient is φ = 16511918080.

The previous prime is 21203210057. The next prime is 21203210069. The reversal of 21203210065 is 56001230212.

It can be written as a sum of positive squares in 8 ways, for example, as 2102864449 + 19100345616 = 45857^2 + 138204^2 .

It is not a de Polignac number, because 21203210065 - 2³ = 21203210057 is a prime.

It is a super-2 number, since 2×21203210065² (a number of 21 digits) contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (21203210069) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 23134 + ... + 207223.

It is an arithmetic number, because the mean of its divisors is an integer number (1632662325).

Almost surely, 2^21203210065 is an apocalyptic number.

It is an amenable number.

21203210065 is a deficient number, since it is larger than the sum of its proper divisors (4919387135).

21203210065 is a wasteful number, since it uses less digits than its factorization.

21203210065 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 230852.

The product of its (nonzero) digits is 720, while the sum is 22.

Adding to 21203210065 its reverse (56001230212), we get a palindrome (77204440277).

The spelling of 21203210065 in words is "twenty-one billion, two hundred three million, two hundred ten thousand, sixty-five".