1662543121 has 2 divisors, whose sum is σ = 1662543122. Its totient is φ = 1662543120.

The previous prime is 1662543119. The next prime is 1662543133. The reversal of 1662543121 is 1213452661.

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., 1516012096 + 146531025 = 38936^2 + 12105^2 .

It is a cyclic number.

It is not a de Polignac number, because 1662543121 - 2¹ = 1662543119 is a prime.

Together with 1662543119, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (1662543161) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 831271560 + 831271561.

It is an arithmetic number, because the mean of its divisors is an integer number (831271561).

Almost surely, 2^1662543121 is an apocalyptic number.

It is an amenable number.

1662543121 is a deficient number, since it is larger than the sum of its proper divisors (1).

1662543121 is an equidigital number, since it uses as much as digits as its factorization.

1662543121 is an evil number, because the sum of its binary digits is even.

The product of its digits is 8640, while the sum is 31.

The square root of 1662543121 is about 40774.2948559506. The cubic root of 1662543121 is about 1184.6524931870.

Adding to 1662543121 its reverse (1213452661), we get a palindrome (2875995782).

The spelling of 1662543121 in words is "one billion, six hundred sixty-two million, five hundred forty-three thousand, one hundred twenty-one".