724909921 has 4 divisors (see below), whose sum is σ = 748294144. Its totient is φ = 701525700.

The previous prime is 724909873. The next prime is 724909949. The reversal of 724909921 is 129909427.

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 724909921 - 2¹¹ = 724907873 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (724909951) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 11692065 + ... + 11692126.

It is an arithmetic number, because the mean of its divisors is an integer number (187073536).

Almost surely, 2^724909921 is an apocalyptic number.

It is an amenable number.

724909921 is a deficient number, since it is larger than the sum of its proper divisors (23384223).

724909921 is a wasteful number, since it uses less digits than its factorization.

724909921 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 23384222.

The product of its (nonzero) digits is 81648, while the sum is 43.

The square root of 724909921 is about 26924.1512586748. The cubic root of 724909921 is about 898.3136822605.

The spelling of 724909921 in words is "seven hundred twenty-four million, nine hundred nine thousand, nine hundred twenty-one".