721809097 has 4 divisors (see below), whose sum is σ = 722284560. Its totient is φ = 721333636.

The previous prime is 721809089. The next prime is 721809119. The reversal of 721809097 is 790908127.

It is a happy number.

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, and also an emirpimes, since its reverse is a distinct semiprime: 790908127 = 61 ⋅12965707.

It is a cyclic number.

It is not a de Polignac number, because 721809097 - 2³ = 721809089 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (721809007) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 235447 + ... + 238492.

It is an arithmetic number, because the mean of its divisors is an integer number (180571140).

Almost surely, 2^721809097 is an apocalyptic number.

It is an amenable number.

721809097 is a deficient number, since it is larger than the sum of its proper divisors (475463).

721809097 is a wasteful number, since it uses less digits than its factorization.

721809097 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 475462.

The product of its (nonzero) digits is 63504, while the sum is 43.

The square root of 721809097 is about 26866.5051132446. The cubic root of 721809097 is about 897.0309970078.

The spelling of 721809097 in words is "seven hundred twenty-one million, eight hundred nine thousand, ninety-seven".