1605772121 has 2 divisors, whose sum is σ = 1605772122. Its totient is φ = 1605772120.

The previous prime is 1605772039. The next prime is 1605772123. The reversal of 1605772121 is 1212775061.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 1605124096 + 648025 = 40064^2 + 805^2 .

It is a cyclic number.

It is not a de Polignac number, because 1605772121 - 2³⁰ = 532030297 is a prime.

Together with 1605772123, it forms a pair of twin primes.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (1605772123) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 802886060 + 802886061.

It is an arithmetic number, because the mean of its divisors is an integer number (802886061).

Almost surely, 2^1605772121 is an apocalyptic number.

It is an amenable number.

1605772121 is a deficient number, since it is larger than the sum of its proper divisors (1).

1605772121 is an equidigital number, since it uses as much as digits as its factorization.

1605772121 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 5880, while the sum is 32.

The square root of 1605772121 is about 40072.0865566045. The cubic root of 1605772121 is about 1171.0118893526.

The spelling of 1605772121 in words is "one billion, six hundred five million, seven hundred seventy-two thousand, one hundred twenty-one".