1915721 has 2 divisors, whose sum is σ = 1915722. Its totient is φ = 1915720.

The previous prime is 1915703. The next prime is 1915729. The reversal of 1915721 is 1275191.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 1860496 + 55225 = 1364^2 + 235^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1915721 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (1915729) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 957860 + 957861.

It is an arithmetic number, because the mean of its divisors is an integer number (957861).

2^1915721 is an apocalyptic number.

It is an amenable number.

1915721 is a deficient number, since it is larger than the sum of its proper divisors (1).

1915721 is an equidigital number, since it uses as much as digits as its factorization.

1915721 is an evil number, because the sum of its binary digits is even.

The product of its digits is 630, while the sum is 26.

The square root of 1915721 is about 1384.0957336832. The cubic root of 1915721 is about 124.1968992841.

The spelling of 1915721 in words is "one million, nine hundred fifteen thousand, seven hundred twenty-one".