1601187821 has 2 divisors, whose sum is σ = 1601187822. Its totient is φ = 1601187820.

The previous prime is 1601187781. The next prime is 1601187877. The reversal of 1601187821 is 1287811061.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1340365321 + 260822500 = 36611^2 + 16150^2 .

It is an emirp because it is prime and its reverse (1287811061) is a distict prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1601187821 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1601187521) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 800593910 + 800593911.

It is an arithmetic number, because the mean of its divisors is an integer number (800593911).

Almost surely, 2^1601187821 is an apocalyptic number.

It is an amenable number.

1601187821 is a deficient number, since it is larger than the sum of its proper divisors (1).

1601187821 is an equidigital number, since it uses as much as digits as its factorization.

1601187821 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 5376, while the sum is 35.

The square root of 1601187821 is about 40014.8450078218. The cubic root of 1601187821 is about 1169.8964578300.

Adding to 1601187821 its reverse (1287811061), we get a palindrome (2888998882).

The spelling of 1601187821 in words is "one billion, six hundred one million, one hundred eighty-seven thousand, eight hundred twenty-one".