20399235881 has 2 divisors, whose sum is σ = 20399235882. Its totient is φ = 20399235880.

The previous prime is 20399235853. The next prime is 20399235887. The reversal of 20399235881 is 18853299302.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 18220680256 + 2178555625 = 134984^2 + 46675^2 .

It is a cyclic number.

It is not a de Polignac number, because 20399235881 - 2³⁰ = 19325494057 is a prime.

It is a super-2 number, since 2×20399235881² (a number of 21 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (20399235887) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10199617940 + 10199617941.

It is an arithmetic number, because the mean of its divisors is an integer number (10199617941).

Almost surely, 2^20399235881 is an apocalyptic number.

It is an amenable number.

20399235881 is a deficient number, since it is larger than the sum of its proper divisors (1).

20399235881 is an equidigital number, since it uses as much as digits as its factorization.

20399235881 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 933120, while the sum is 50.

The spelling of 20399235881 in words is "twenty billion, three hundred ninety-nine million, two hundred thirty-five thousand, eight hundred eighty-one".