1642661 has 2 divisors, whose sum is σ = 1642662. Its totient is φ = 1642660.

The previous prime is 1642657. The next prime is 1642679. The reversal of 1642661 is 1662461.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1600225 + 42436 = 1265^2 + 206^2 .

It is a cyclic number.

It is not a de Polignac number, because 1642661 - 2² = 1642657 is a prime.

It is a Chen prime.

It is a plaindrome in base 15.

It is a self number, because there is not a number n which added to its sum of digits gives 1642661.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1642601) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 821330 + 821331.

It is an arithmetic number, because the mean of its divisors is an integer number (821331).

2^1642661 is an apocalyptic number.

It is an amenable number.

1642661 is a deficient number, since it is larger than the sum of its proper divisors (1).

1642661 is an equidigital number, since it uses as much as digits as its factorization.

1642661 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1728, while the sum is 26.

The square root of 1642661 is about 1281.6633723408. The cubic root of 1642661 is about 117.9911177840.

The spelling of 1642661 in words is "one million, six hundred forty-two thousand, six hundred sixty-one".