20511320235261 has 32 divisors (see below), whose sum is σ = 29072107249920. Its totient is φ = 12818767282176.

The previous prime is 20511320235251. The next prime is 20511320235281. The reversal of 20511320235261 is 16253202311502.

It is not a de Polignac number, because 20511320235261 - 2²³ = 20511311846653 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20511320235251) 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, 189853320 + ... + 189961326.

It is an arithmetic number, because the mean of its divisors is an integer number (908503351560).

Almost surely, 2^{20511320235261} is an apocalyptic number.

It is an amenable number.

20511320235261 is a deficient number, since it is larger than the sum of its proper divisors (8560787014659).

20511320235261 is a wasteful number, since it uses less digits than its factorization.

20511320235261 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 122773.

The product of its (nonzero) digits is 21600, while the sum is 33.

Adding to 20511320235261 its reverse (16253202311502), we get a palindrome (36764522546763).

The spelling of 20511320235261 in words is "twenty trillion, five hundred eleven billion, three hundred twenty million, two hundred thirty-five thousand, two hundred sixty-one".