721090081 has 4 divisors (see below), whose sum is σ = 725865664. Its totient is φ = 716314500.

The previous prime is 721090061. The next prime is 721090087. The reversal of 721090081 is 180090127.

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 721090081 - 2¹⁵ = 721057313 is a prime.

It is a super-2 number, since 2×721090081² = 1039941809833173122, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (721090087) 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, 2387565 + ... + 2387866.

It is an arithmetic number, because the mean of its divisors is an integer number (181466416).

Almost surely, 2^721090081 is an apocalyptic number.

It is an amenable number.

721090081 is a deficient number, since it is larger than the sum of its proper divisors (4775583).

721090081 is a wasteful number, since it uses less digits than its factorization.

721090081 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4775582.

The product of its (nonzero) digits is 1008, while the sum is 28.

The square root of 721090081 is about 26853.1205076803. The cubic root of 721090081 is about 896.7330447645.

The spelling of 721090081 in words is "seven hundred twenty-one million, ninety thousand, eighty-one".