6861721 has 4 divisors (see below), whose sum is σ = 6867712. Its totient is φ = 6855732.

The previous prime is 6861709. The next prime is 6861733. The reversal of 6861721 is 1271686.

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 a brilliant number, because the two primes have the same length.

It is an interprime number because it is at equal distance from previous prime (6861709) and next prime (6861733).

It is a cyclic number.

It is not a de Polignac number, because 6861721 - 2¹³ = 6853529 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (6861791) 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, 681 + ... + 3766.

It is an arithmetic number, because the mean of its divisors is an integer number (1716928).

Almost surely, 2^6861721 is an apocalyptic number.

It is an amenable number.

6861721 is a deficient number, since it is larger than the sum of its proper divisors (5991).

6861721 is a wasteful number, since it uses less digits than its factorization.

6861721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5990.

The product of its digits is 4032, while the sum is 31.

The square root of 6861721 is about 2619.4886905654. The cubic root of 6861721 is about 190.0251213321.

The spelling of 6861721 in words is "six million, eight hundred sixty-one thousand, seven hundred twenty-one".