159690821 has 2 divisors, whose sum is σ = 159690822. Its totient is φ = 159690820.

The previous prime is 159690803. The next prime is 159690847. The reversal of 159690821 is 128096951.

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., 96805921 + 62884900 = 9839^2 + 7930^2 .

It is an emirp because it is prime and its reverse (128096951) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 159690821 - 2¹⁰ = 159689797 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (159690851) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 79845410 + 79845411.

It is an arithmetic number, because the mean of its divisors is an integer number (79845411).

Almost surely, 2^159690821 is an apocalyptic number.

It is an amenable number.

159690821 is a deficient number, since it is larger than the sum of its proper divisors (1).

159690821 is an equidigital number, since it uses as much as digits as its factorization.

159690821 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 38880, while the sum is 41.

The square root of 159690821 is about 12636.8833578537. The cubic root of 159690821 is about 542.5336141191.

The spelling of 159690821 in words is "one hundred fifty-nine million, six hundred ninety thousand, eight hundred twenty-one".