1641681000961 has 3 divisors (see below), whose sum is σ = 1641682282243. Its totient is φ = 1641679719680.

The previous prime is 1641681000917. The next prime is 1641681000989. The reversal of 1641681000961 is 1690001861461.

The square root of 1641681000961 is 1281281.

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., 157474842561 + 1484206158400 = 396831^2 + 1218280^2 .

It is not a de Polignac number, because 1641681000961 - 2⁷ = 1641681000833 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1641681000901) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 2 ways as a sum of consecutive naturals, for example, 640641 + ... + 1921921.

Almost surely, 2^{1641681000961} is an apocalyptic number.

1641681000961 is the 1281281-st square number.

1641681000961 is the 640641-st centered octagonal number.

It is an amenable number.

1641681000961 is a deficient number, since it is larger than the sum of its proper divisors (1281282).

1641681000961 is an frugal number, since it uses more digits than its factorization.

1641681000961 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2562562 (or 1281281 counting only the distinct ones).

The product of its (nonzero) digits is 62208, while the sum is 43.

The spelling of 1641681000961 in words is "one trillion, six hundred forty-one billion, six hundred eighty-one million, nine hundred sixty-one", and thus it is an aban number.