1722991 has 2 divisors, whose sum is σ = 1722992. Its totient is φ = 1722990.

The previous prime is 1722989. The next prime is 1723003. The reversal of 1722991 is 1992271.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 1722991 - 2¹ = 1722989 is a prime.

Together with 1722989, it forms a pair of twin primes.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1722191) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 861495 + 861496.

It is an arithmetic number, because the mean of its divisors is an integer number (861496).

2^1722991 is an apocalyptic number.

1722991 is a deficient number, since it is larger than the sum of its proper divisors (1).

1722991 is an equidigital number, since it uses as much as digits as its factorization.

1722991 is an evil number, because the sum of its binary digits is even.

The product of its digits is 2268, while the sum is 31.

The square root of 1722991 is about 1312.6275176150. The cubic root of 1722991 is about 119.8839387103.

The spelling of 1722991 in words is "one million, seven hundred twenty-two thousand, nine hundred ninety-one".