20437540561 has 2 divisors, whose sum is σ = 20437540562. Its totient is φ = 20437540560.

The previous prime is 20437540553. The next prime is 20437540603. The reversal of 20437540561 is 16504573402.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 17598675600 + 2838864961 = 132660^2 + 53281^2 .

It is a cyclic number.

It is not a de Polignac number, because 20437540561 - 2³ = 20437540553 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 20437540561.

It is not a weakly prime, because it can be changed into another prime (20437540061) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10218770280 + 10218770281.

It is an arithmetic number, because the mean of its divisors is an integer number (10218770281).

Almost surely, 2^20437540561 is an apocalyptic number.

It is an amenable number.

20437540561 is a deficient number, since it is larger than the sum of its proper divisors (1).

20437540561 is an equidigital number, since it uses as much as digits as its factorization.

20437540561 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 100800, while the sum is 37.

The spelling of 20437540561 in words is "twenty billion, four hundred thirty-seven million, five hundred forty thousand, five hundred sixty-one".