1801722561 has 4 divisors (see below), whose sum is σ = 2402296752. Its totient is φ = 1201148372.

The previous prime is 1801722547. The next prime is 1801722569. The reversal of 1801722561 is 1652271081.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 1801722561 - 2⁹ = 1801722049 is a prime.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (1801722569) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 300287091 + ... + 300287096.

It is an arithmetic number, because the mean of its divisors is an integer number (600574188).

Almost surely, 2^1801722561 is an apocalyptic number.

It is an amenable number.

1801722561 is a deficient number, since it is larger than the sum of its proper divisors (600574191).

1801722561 is an equidigital number, since it uses as much as digits as its factorization.

1801722561 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 600574190.

The product of its (nonzero) digits is 6720, while the sum is 33.

The square root of 1801722561 is about 42446.7025927810. The cubic root of 1801722561 is about 1216.8283111018.

The spelling of 1801722561 in words is "one billion, eight hundred one million, seven hundred twenty-two thousand, five hundred sixty-one".