20406887569 has 2 divisors, whose sum is σ = 20406887570. Its totient is φ = 20406887568.

The previous prime is 20406887551. The next prime is 20406887581. The reversal of 20406887569 is 96578860402.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 15349971025 + 5056916544 = 123895^2 + 71112^2 .

It is a cyclic number.

It is not a de Polignac number, because 20406887569 - 2⁷ = 20406887441 is a prime.

It is a super-2 number, since 2×20406887569² (a number of 21 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (20406887539) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10203443784 + 10203443785.

It is an arithmetic number, because the mean of its divisors is an integer number (10203443785).

Almost surely, 2^20406887569 is an apocalyptic number.

It is an amenable number.

20406887569 is a deficient number, since it is larger than the sum of its proper divisors (1).

20406887569 is an equidigital number, since it uses as much as digits as its factorization.

20406887569 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 5806080, while the sum is 55.

The spelling of 20406887569 in words is "twenty billion, four hundred six million, eight hundred eighty-seven thousand, five hundred sixty-nine".