2121640236365 has 32 divisors (see below), whose sum is σ = 2911413909600. Its totient is φ = 1470362517504.

The previous prime is 2121640236337. The next prime is 2121640236389. The reversal of 2121640236365 is 5636320461212.

It can be written as a sum of positive squares in 16 ways, for example, as 198151400164 + 1923488836201 = 445142^2 + 1386899^2 .

It is a cyclic number.

It is not a de Polignac number, because 2121640236365 - 2⁶ = 2121640236301 is a prime.

It is a Curzon number.

It is a congruent number.

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, 2365124 + ... + 3136413.

It is an arithmetic number, because the mean of its divisors is an integer number (90981684675).

Almost surely, 2^{2121640236365} is an apocalyptic number.

It is an amenable number.

2121640236365 is a deficient number, since it is larger than the sum of its proper divisors (789773673235).

2121640236365 is a wasteful number, since it uses less digits than its factorization.

2121640236365 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5501921.

The product of its (nonzero) digits is 311040, while the sum is 41.

Adding to 2121640236365 its reverse (5636320461212), we get a palindrome (7757960697577).

The spelling of 2121640236365 in words is "two trillion, one hundred twenty-one billion, six hundred forty million, two hundred thirty-six thousand, three hundred sixty-five".