1205721 has 24 divisors (see below), whose sum is σ = 2003040. Its totient is φ = 691200.

The previous prime is 1205717. The next prime is 1205731. The reversal of 1205721 is 1275021.

It is not a de Polignac number, because 1205721 - 2² = 1205717 is a prime.

It is a plaindrome in base 14.

It is a junction number, because it is equal to n+sod(n) for n = 1205694 and 1205703.

It is not an unprimeable number, because it can be changed into a prime (1205731) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 1561 + ... + 2201.

It is an arithmetic number, because the mean of its divisors is an integer number (83460).

2^1205721 is an apocalyptic number.

1205721 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

It is an amenable number.

1205721 is a deficient number, since it is larger than the sum of its proper divisors (797319).

1205721 is a wasteful number, since it uses less digits than its factorization.

1205721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 677 (or 674 counting only the distinct ones).

The product of its (nonzero) digits is 140, while the sum is 18.

The square root of 1205721 is about 1098.0532773960. The cubic root of 1205721 is about 106.4344634153.

The spelling of 1205721 in words is "one million, two hundred five thousand, seven hundred twenty-one".