20856434461 has 2 divisors, whose sum is σ = 20856434462. Its totient is φ = 20856434460.

The previous prime is 20856434453. The next prime is 20856434483. The reversal of 20856434461 is 16443465802.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 13975731961 + 6880702500 = 118219^2 + 82950^2 .

It is a cyclic number.

It is not a de Polignac number, because 20856434461 - 2³ = 20856434453 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20856434441) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10428217230 + 10428217231.

It is an arithmetic number, because the mean of its divisors is an integer number (10428217231).

Almost surely, 2^20856434461 is an apocalyptic number.

It is an amenable number.

20856434461 is a deficient number, since it is larger than the sum of its proper divisors (1).

20856434461 is an equidigital number, since it uses as much as digits as its factorization.

20856434461 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 552960, while the sum is 43.

The spelling of 20856434461 in words is "twenty billion, eight hundred fifty-six million, four hundred thirty-four thousand, four hundred sixty-one".