1671721 has 4 divisors (see below), whose sum is σ = 1682944. Its totient is φ = 1660500.

The previous prime is 1671713. The next prime is 1671727. The reversal of 1671721 is 1271761.

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, and also an emirpimes, since its reverse is a distinct semiprime: 1271761 = 521 ⋅2441.

It is a cyclic number.

It is not a de Polignac number, because 1671721 - 2³ = 1671713 is a prime.

It is a super-2 number, since 2×1671721² = 5589302203682, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1671727) 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, 5385 + ... + 5686.

It is an arithmetic number, because the mean of its divisors is an integer number (420736).

2^1671721 is an apocalyptic number.

It is an amenable number.

1671721 is a deficient number, since it is larger than the sum of its proper divisors (11223).

1671721 is a wasteful number, since it uses less digits than its factorization.

1671721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 11222.

The product of its digits is 588, while the sum is 25.

The square root of 1671721 is about 1292.9505017594. The cubic root of 1671721 is about 118.6828406954.

The spelling of 1671721 in words is "one million, six hundred seventy-one thousand, seven hundred twenty-one".