993905621 has 4 divisors (see below), whose sum is σ = 995192172. Its totient is φ = 992619072.

The previous prime is 993905593. The next prime is 993905623. The reversal of 993905621 is 126509399.

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 345439396 + 648466225 = 18586^2 + 25465^2 .

It is a cyclic number.

It is not a de Polignac number, because 993905621 - 2¹⁸ = 993643477 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (993905623) 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, 642116 + ... + 643661.

It is an arithmetic number, because the mean of its divisors is an integer number (248798043).

Almost surely, 2^993905621 is an apocalyptic number.

It is an amenable number.

993905621 is a deficient number, since it is larger than the sum of its proper divisors (1286551).

993905621 is a wasteful number, since it uses less digits than its factorization.

993905621 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1286550.

The product of its (nonzero) digits is 131220, while the sum is 44.

The square root of 993905621 is about 31526.2687452860. The cubic root of 993905621 is about 997.9643994755.

The spelling of 993905621 in words is "nine hundred ninety-three million, nine hundred five thousand, six hundred twenty-one".