820159421 has 2 divisors, whose sum is σ = 820159422. Its totient is φ = 820159420.

The previous prime is 820159409. The next prime is 820159463. The reversal of 820159421 is 124951028.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 582691321 + 237468100 = 24139^2 + 15410^2 .

It is a cyclic number.

It is not a de Polignac number, because 820159421 - 2¹⁰ = 820158397 is a prime.

It is a super-2 number, since 2×820159421² = 1345322951710110482, which contains 22 as substring.

It is a Sophie Germain prime.

It is a Curzon number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (820159481) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 410079710 + 410079711.

It is an arithmetic number, because the mean of its divisors is an integer number (410079711).

Almost surely, 2^820159421 is an apocalyptic number.

It is an amenable number.

820159421 is a deficient number, since it is larger than the sum of its proper divisors (1).

820159421 is an equidigital number, since it uses as much as digits as its factorization.

820159421 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 5760, while the sum is 32.

The square root of 820159421 is about 28638.4256026759. The cubic root of 820159421 is about 936.0508154924.

The spelling of 820159421 in words is "eight hundred twenty million, one hundred fifty-nine thousand, four hundred twenty-one".