2161438661 has 2 divisors, whose sum is σ = 2161438662. Its totient is φ = 2161438660.

The previous prime is 2161438649. The next prime is 2161438673. The reversal of 2161438661 is 1668341612.

2161438661 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a balanced prime because it is at equal distance from previous prime (2161438649) and next prime (2161438673).

It can be written as a sum of positive squares in only one way, i.e., 1825852900 + 335585761 = 42730^2 + 18319^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-2161438661 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (2161438061) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1080719330 + 1080719331.

It is an arithmetic number, because the mean of its divisors is an integer number (1080719331).

Almost surely, 2^2161438661 is an apocalyptic number.

It is an amenable number.

2161438661 is a deficient number, since it is larger than the sum of its proper divisors (1).

2161438661 is an equidigital number, since it uses as much as digits as its factorization.

2161438661 is an evil number, because the sum of its binary digits is even.

The product of its digits is 41472, while the sum is 38.

The square root of 2161438661 is about 46491.2751061960. The cubic root of 2161438661 is about 1292.9477411749.

The spelling of 2161438661 in words is "two billion, one hundred sixty-one million, four hundred thirty-eight thousand, six hundred sixty-one".