2139661 has 2 divisors, whose sum is σ = 2139662. Its totient is φ = 2139660.

The previous prime is 2139659. The next prime is 2139677. The reversal of 2139661 is 1669312.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1425636 + 714025 = 1194^2 + 845^2 .

It is a cyclic number.

It is not a de Polignac number, because 2139661 - 2¹ = 2139659 is a prime.

Together with 2139659, it forms a pair of twin primes.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (2139611) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1069830 + 1069831.

It is an arithmetic number, because the mean of its divisors is an integer number (1069831).

2^2139661 is an apocalyptic number.

It is an amenable number.

2139661 is a deficient number, since it is larger than the sum of its proper divisors (1).

2139661 is an equidigital number, since it uses as much as digits as its factorization.

2139661 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1944, while the sum is 28.

The square root of 2139661 is about 1462.7580114291. The cubic root of 2139661 is about 128.8590692950.

The spelling of 2139661 in words is "two million, one hundred thirty-nine thousand, six hundred sixty-one".