721520242 has 8 divisors (see below), whose sum is σ = 1082397276. Its totient is φ = 360721152.

The previous prime is 721520237. The next prime is 721520279. The reversal of 721520242 is 242025127.

It can be written as a sum of positive squares in 2 ways, for example, as 670240321 + 51279921 = 25889^2 + 7161^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 18358 + ... + 42190.

Almost surely, 2^721520242 is an apocalyptic number.

721520242 is a deficient number, since it is larger than the sum of its proper divisors (360877034).

721520242 is a wasteful number, since it uses less digits than its factorization.

721520242 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 38972.

The product of its (nonzero) digits is 2240, while the sum is 25.

The square root of 721520242 is about 26861.1288295931. The cubic root of 721520242 is about 896.9113224931.

Adding to 721520242 its reverse (242025127), we get a palindrome (963545369).

The spelling of 721520242 in words is "seven hundred twenty-one million, five hundred twenty thousand, two hundred forty-two".