1999138660281 has 63 divisors (see below), whose sum is σ = 3487164091743. Its totient is φ = 1142212246560.

The previous prime is 1999138660151. The next prime is 1999138660289. The reversal of 1999138660281 is 1820668319991.

The square root of 1999138660281 is 1413909.

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

1999138660281 is a `hidden beast` number, since 1 + 9 + 9 + 9 + 13 + 8 + 6 + 602 + 8 + 1 = 666.

It can be written as a sum of positive squares in only one way, i.e., 1734860413881 + 264278246400 = 1317141^2 + 514080^2 .

It is a tau number, because it is divible by the number of its divisors (63).

It is not a de Polignac number, because 1999138660281 - 2⁹ = 1999138659769 is a prime.

It is a super-2 number, since 2×1999138660281² (a number of 25 digits) contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (63).

It is not an unprimeable number, because it can be changed into a prime (1999138660289) by changing a digit.

It is a polite number, since it can be written in 62 ways as a sum of consecutive naturals, for example, 267225061 + ... + 267232541.

Almost surely, 2^{1999138660281} is an apocalyptic number.

1999138660281 is the 1413909-th square number.

1999138660281 is the 706955-th centered octagonal number.

It is an amenable number.

1999138660281 is a deficient number, since it is larger than the sum of its proper divisors (1488025431462).

1999138660281 is an frugal number, since it uses more digits than its factorization.

1999138660281 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 14994 (or 7491 counting only the distinct ones).

The product of its (nonzero) digits is 10077696, while the sum is 63.

The spelling of 1999138660281 in words is "one trillion, nine hundred ninety-nine billion, one hundred thirty-eight million, six hundred sixty thousand, two hundred eighty-one".