993721 has 4 divisors (see below), whose sum is σ = 1014912. Its totient is φ = 972532.

The previous prime is 993703. The next prime is 993763. The reversal of 993721 is 127399.

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.

It is a cyclic number.

It is not a de Polignac number, because 993721 - 2⁵ = 993689 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (993781) 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, 10525 + ... + 10618.

It is an arithmetic number, because the mean of its divisors is an integer number (253728).

2⁹⁹³⁷²¹ is an apocalyptic number.

It is an amenable number.

993721 is a deficient number, since it is larger than the sum of its proper divisors (21191).

993721 is a wasteful number, since it uses less digits than its factorization.

993721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 21190.

The product of its digits is 3402, while the sum is 31.

The square root of 993721 is about 996.8555562367. The cubic root of 993721 is about 99.7902604006.

The spelling of 993721 in words is "nine hundred ninety-three thousand, seven hundred twenty-one".