721617545 has 16 divisors (see below), whose sum is σ = 947047680. Its totient is φ = 523488000.

The previous prime is 721617541. The next prime is 721617563. The reversal of 721617545 is 545716127.

It is not a de Polignac number, because 721617545 - 2² = 721617541 is a prime.

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 721617499 and 721617508.

It is not an unprimeable number, because it can be changed into a prime (721617541) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 5696 + ... + 38414.

It is an arithmetic number, because the mean of its divisors is an integer number (59190480).

Almost surely, 2^721617545 is an apocalyptic number.

It is an amenable number.

721617545 is a deficient number, since it is larger than the sum of its proper divisors (225430135).

721617545 is a wasteful number, since it uses less digits than its factorization.

721617545 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 33136.

The product of its digits is 58800, while the sum is 38.

The square root of 721617545 is about 26862.9399917433. The cubic root of 721617545 is about 896.9516393290.

The spelling of 721617545 in words is "seven hundred twenty-one million, six hundred seventeen thousand, five hundred forty-five".