613721 has 4 divisors (see below), whose sum is σ = 623844. Its totient is φ = 603600.

The previous prime is 613699. The next prime is 613733. The reversal of 613721 is 127316.

It is a happy number.

613721 is nontrivially palindromic in base 16.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 151321 + 462400 = 389^2 + 680^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-613721 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 613693 and 613702.

It is not an unprimeable number, because it can be changed into a prime (613741) 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 3 ways as a sum of consecutive naturals, for example, 4970 + ... + 5091.

It is an arithmetic number, because the mean of its divisors is an integer number (155961).

2⁶¹³⁷²¹ is an apocalyptic number.

613721 is a gapful number since it is divisible by the number (61) formed by its first and last digit.

It is an amenable number.

613721 is a deficient number, since it is larger than the sum of its proper divisors (10123).

613721 is a wasteful number, since it uses less digits than its factorization.

613721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10122.

The product of its digits is 252, while the sum is 20.

The square root of 613721 is about 783.4034720372. The cubic root of 613721 is about 84.9813569263.

It can be divided in two parts, 61 and 3721, that multiplied together give a cube (226981 = 61³).

The spelling of 613721 in words is "six hundred thirteen thousand, seven hundred twenty-one".