721691045 has 8 divisors (see below), whose sum is σ = 866829600. Its totient is φ = 576819280.

The previous prime is 721691039. The next prime is 721691057. The reversal of 721691045 is 540196127.

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

It is not a de Polignac number, because 721691045 - 2²⁸ = 453255589 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 721690996 and 721691014.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 60695 + ... + 71604.

It is an arithmetic number, because the mean of its divisors is an integer number (108353700).

Almost surely, 2^721691045 is an apocalyptic number.

It is an amenable number.

721691045 is a deficient number, since it is larger than the sum of its proper divisors (145138555).

721691045 is a wasteful number, since it uses less digits than its factorization.

721691045 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 133395.

The product of its (nonzero) digits is 15120, while the sum is 35.

The square root of 721691045 is about 26864.3080126773. The cubic root of 721691045 is about 896.9820911511.

The spelling of 721691045 in words is "seven hundred twenty-one million, six hundred ninety-one thousand, forty-five".