1994927431561 has 3 divisors (see below), whose sum is σ = 1994928843981. Its totient is φ = 1994926019142.

The previous prime is 1994927431513. The next prime is 1994927431603. The reversal of 1994927431561 is 1651347294991.

The square root of 1994927431561 is 1412419.

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 is not a de Polignac number, because 1994927431561 - 2⁷ = 1994927431433 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 1994927431561.

It is not an unprimeable number, because it can be changed into a prime (1994927431261) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 2 ways as a sum of consecutive naturals, for example, 706210 + ... + 2118628.

It is an arithmetic number, because the mean of its divisors is an integer number (664976281327).

Almost surely, 2^{1994927431561} is an apocalyptic number.

1994927431561 is the 1412419-th square number.

1994927431561 is the 706210-th centered octagonal number.

It is an amenable number.

1994927431561 is a deficient number, since it is larger than the sum of its proper divisors (1412420).

1994927431561 is an frugal number, since it uses more digits than its factorization.

1994927431561 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2824838 (or 1412419 counting only the distinct ones).

The product of its digits is 14696640, while the sum is 61.

The spelling of 1994927431561 in words is "one trillion, nine hundred ninety-four billion, nine hundred twenty-seven million, four hundred thirty-one thousand, five hundred sixty-one".