2161641544621 has 8 divisors (see below), whose sum is σ = 2327936194584. Its totient is φ = 1995348970560.

The previous prime is 2161641544597. The next prime is 2161641544637. The reversal of 2161641544621 is 1264451461612.

It is a happy number.

It can be written as a sum of positive squares in 4 ways, for example, as 178135487721 + 1983506056900 = 422061^2 + 1408370^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 2161641544621 - 2¹³ = 2161641536429 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (2161641554621) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 2153451 + ... + 2993431.

It is an arithmetic number, because the mean of its divisors is an integer number (290992024323).

Almost surely, 2^{2161641544621} is an apocalyptic number.

It is an amenable number.

2161641544621 is a deficient number, since it is larger than the sum of its proper divisors (166294649963).

2161641544621 is a wasteful number, since it uses less digits than its factorization.

2161641544621 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1037951.

The product of its digits is 276480, while the sum is 43.

The spelling of 2161641544621 in words is "two trillion, one hundred sixty-one billion, six hundred forty-one million, five hundred forty-four thousand, six hundred twenty-one".