20856554437 has 2 divisors, whose sum is σ = 20856554438. Its totient is φ = 20856554436.

The previous prime is 20856554413. The next prime is 20856554443. The reversal of 20856554437 is 73445565802.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 19132145761 + 1724408676 = 138319^2 + 41526^2 .

It is a cyclic number.

It is not a de Polignac number, because 20856554437 - 2¹⁹ = 20856030149 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20856551437) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10428277218 + 10428277219.

It is an arithmetic number, because the mean of its divisors is an integer number (10428277219).

Almost surely, 2^20856554437 is an apocalyptic number.

It is an amenable number.

20856554437 is a deficient number, since it is larger than the sum of its proper divisors (1).

20856554437 is an equidigital number, since it uses as much as digits as its factorization.

20856554437 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 4032000, while the sum is 49.

The spelling of 20856554437 in words is "twenty billion, eight hundred fifty-six million, five hundred fifty-four thousand, four hundred thirty-seven".