642161521 has 2 divisors, whose sum is σ = 642161522. Its totient is φ = 642161520.

The previous prime is 642161503. The next prime is 642161537. The reversal of 642161521 is 125161246.

642161521 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 626951521 + 15210000 = 25039^2 + 3900^2 .

It is a cyclic number.

It is not a de Polignac number, because 642161521 - 2¹³ = 642153329 is a prime.

It is a Chen prime.

It is a self number, because there is not a number n which added to its sum of digits gives 642161521.

It is not a weakly prime, because it can be changed into another prime (642161591) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 321080760 + 321080761.

It is an arithmetic number, because the mean of its divisors is an integer number (321080761).

Almost surely, 2^642161521 is an apocalyptic number.

It is an amenable number.

642161521 is a deficient number, since it is larger than the sum of its proper divisors (1).

642161521 is an equidigital number, since it uses as much as digits as its factorization.

642161521 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 2880, while the sum is 28.

The square root of 642161521 is about 25340.9060808804. The cubic root of 642161521 is about 862.7429641354.

The spelling of 642161521 in words is "six hundred forty-two million, one hundred sixty-one thousand, five hundred twenty-one".