1721366921 has 8 divisors (see below), whose sum is σ = 1812346080. Its totient is φ = 1630425888.

The previous prime is 1721366903. The next prime is 1721366929. The reversal of 1721366921 is 1296631271.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 1721366921 - 2¹⁰ = 1721365897 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1721366929) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 170990 + ... + 180776.

It is an arithmetic number, because the mean of its divisors is an integer number (226543260).

Almost surely, 2^1721366921 is an apocalyptic number.

It is an amenable number.

1721366921 is a deficient number, since it is larger than the sum of its proper divisors (90979159).

1721366921 is an equidigital number, since it uses as much as digits as its factorization.

1721366921 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 19063.

The product of its digits is 27216, while the sum is 38.

The square root of 1721366921 is about 41489.3591297817. The cubic root of 1721366921 is about 1198.4625962121.

The spelling of 1721366921 in words is "one billion, seven hundred twenty-one million, three hundred sixty-six thousand, nine hundred twenty-one".