1642505861 has 2 divisors, whose sum is σ = 1642505862. Its totient is φ = 1642505860.

The previous prime is 1642505803. The next prime is 1642505867. The reversal of 1642505861 is 1685052461.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 1584517636 + 57988225 = 39806^2 + 7615^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1642505861 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1642505867) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 821252930 + 821252931.

It is an arithmetic number, because the mean of its divisors is an integer number (821252931).

Almost surely, 2^1642505861 is an apocalyptic number.

It is an amenable number.

1642505861 is a deficient number, since it is larger than the sum of its proper divisors (1).

1642505861 is an equidigital number, since it uses as much as digits as its factorization.

1642505861 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 57600, while the sum is 38.

The square root of 1642505861 is about 40527.8405667018. The cubic root of 1642505861 is about 1179.8740316071.

The spelling of 1642505861 in words is "one billion, six hundred forty-two million, five hundred five thousand, eight hundred sixty-one".