18705631949 has 2 divisors, whose sum is σ = 18705631950. Its totient is φ = 18705631948.

The previous prime is 18705631933. The next prime is 18705631951. The reversal of 18705631949 is 94913650781.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 14750102500 + 3955529449 = 121450^2 + 62893^2 .

It is a cyclic number.

It is not a de Polignac number, because 18705631949 - 2⁴ = 18705631933 is a prime.

It is a super-2 number, since 2×18705631949² (a number of 21 digits) contains 22 as substring.

Together with 18705631951, it forms a pair of twin primes.

It is a Chen prime.

It is a self number, because there is not a number n which added to its sum of digits gives 18705631949.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (18705631969) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9352815974 + 9352815975.

It is an arithmetic number, because the mean of its divisors is an integer number (9352815975).

Almost surely, 2^18705631949 is an apocalyptic number.

It is an amenable number.

18705631949 is a deficient number, since it is larger than the sum of its proper divisors (1).

18705631949 is an equidigital number, since it uses as much as digits as its factorization.

18705631949 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1632960, while the sum is 53.

The spelling of 18705631949 in words is "eighteen billion, seven hundred five million, six hundred thirty-one thousand, nine hundred forty-nine".