20423503981 has 2 divisors, whose sum is σ = 20423503982. Its totient is φ = 20423503980.

The previous prime is 20423503889. The next prime is 20423504021. The reversal of 20423503981 is 18930532402.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 19304601481 + 1118902500 = 138941^2 + 33450^2 .

It is a cyclic number.

It is not a de Polignac number, because 20423503981 - 2¹⁹ = 20422979693 is a prime.

It is a super-2 number, since 2×20423503981² (a number of 21 digits) contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 20423503981.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20423503081) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10211751990 + 10211751991.

It is an arithmetic number, because the mean of its divisors is an integer number (10211751991).

Almost surely, 2^20423503981 is an apocalyptic number.

It is an amenable number.

20423503981 is a deficient number, since it is larger than the sum of its proper divisors (1).

20423503981 is an equidigital number, since it uses as much as digits as its factorization.

20423503981 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 51840, while the sum is 37.

The spelling of 20423503981 in words is "twenty billion, four hundred twenty-three million, five hundred three thousand, nine hundred eighty-one".