721043842 has 4 divisors (see below), whose sum is σ = 1081565766. Its totient is φ = 360521920.

The previous prime is 721043833. The next prime is 721043857. The reversal of 721043842 is 248340127.

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

It can be written as a sum of positive squares in only one way, i.e., 629056561 + 91987281 = 25081^2 + 9591^2 .

It is a super-2 number, since 2×721043842² = 1039808444172241928, which contains 22 as substring.

It is a Smith number, since the sum of its digits (31) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 180260959 + ... + 180260962.

Almost surely, 2^721043842 is an apocalyptic number.

721043842 is a deficient number, since it is larger than the sum of its proper divisors (360521924).

721043842 is a wasteful number, since it uses less digits than its factorization.

721043842 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 360521923.

The product of its (nonzero) digits is 10752, while the sum is 31.

The square root of 721043842 is about 26852.2595324863. The cubic root of 721043842 is about 896.7138770596.

Adding to 721043842 its reverse (248340127), we get a palindrome (969383969).

The spelling of 721043842 in words is "seven hundred twenty-one million, forty-three thousand, eight hundred forty-two".