19890181745281 has 3 divisors (see below), whose sum is σ = 19890186205123. Its totient is φ = 19890177285440.

The previous prime is 19890181745279. The next prime is 19890181745303. The reversal of 19890181745281 is 18254718109891.

The square root of 19890181745281 is 4459841.

It is a perfect power (a square), and thus also a powerful number.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It can be written as a sum of positive squares in only one way, i.e., 2435500450881 + 17454681294400 = 1560609^2 + 4177880^2 .

It is not a de Polignac number, because 19890181745281 - 2¹ = 19890181745279 is a prime.

It is a super-2 number, since 2×19890181745281² (a number of 27 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (19890181745081) by changing a digit.

It is a polite number, since it can be written in 2 ways as a sum of consecutive naturals, for example, 2229921 + ... + 6689761.

Almost surely, 2^{19890181745281} is an apocalyptic number.

19890181745281 is the 4459841-st square number.

19890181745281 is the 2229921-st centered octagonal number.

It is an amenable number.

19890181745281 is a deficient number, since it is larger than the sum of its proper divisors (4459842).

19890181745281 is an frugal number, since it uses more digits than its factorization.

19890181745281 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8919682 (or 4459841 counting only the distinct ones).

The product of its (nonzero) digits is 11612160, while the sum is 64.

The spelling of 19890181745281 in words is "nineteen trillion, eight hundred ninety billion, one hundred eighty-one million, seven hundred forty-five thousand, two hundred eighty-one".