721044991 has 2 divisors, whose sum is σ = 721044992. Its totient is φ = 721044990.

The previous prime is 721044971. The next prime is 721045033. The reversal of 721044991 is 199440127.

It is a weak prime.

It is an emirp because it is prime and its reverse (199440127) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 721044991 - 2²¹ = 718947839 is a prime.

It is a Chen prime.

It is a self number, because there is not a number n which added to its sum of digits gives 721044991.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (721044931) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 360522495 + 360522496.

It is an arithmetic number, because the mean of its divisors is an integer number (360522496).

Almost surely, 2^721044991 is an apocalyptic number.

721044991 is a deficient number, since it is larger than the sum of its proper divisors (1).

721044991 is an equidigital number, since it uses as much as digits as its factorization.

721044991 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 18144, while the sum is 37.

The square root of 721044991 is about 26852.2809273253. The cubic root of 721044991 is about 896.7143533708.

The spelling of 721044991 in words is "seven hundred twenty-one million, forty-four thousand, nine hundred ninety-one".