20321101125561 has 4 divisors (see below), whose sum is σ = 27094801500752. Its totient is φ = 13547400750372.

The previous prime is 20321101125541. The next prime is 20321101125607. The reversal of 20321101125561 is 16552110112302.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is not a de Polignac number, because 20321101125561 - 2³¹ = 20318953641913 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20321101125541) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3386850187591 + ... + 3386850187596.

It is an arithmetic number, because the mean of its divisors is an integer number (6773700375188).

Almost surely, 2^{20321101125561} is an apocalyptic number.

It is an amenable number.

20321101125561 is a deficient number, since it is larger than the sum of its proper divisors (6773700375191).

20321101125561 is an equidigital number, since it uses as much as digits as its factorization.

20321101125561 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6773700375190.

The product of its (nonzero) digits is 3600, while the sum is 30.

Adding to 20321101125561 its reverse (16552110112302), we get a palindrome (36873211237863).

The spelling of 20321101125561 in words is "twenty trillion, three hundred twenty-one billion, one hundred one million, one hundred twenty-five thousand, five hundred sixty-one".