721540031 has 8 divisors (see below), whose sum is σ = 725833728. Its totient is φ = 717255000.

The previous prime is 721540019. The next prime is 721540037. The reversal of 721540031 is 130045127.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-721540031 is a prime.

It is a super-2 number, since 2×721540031² = 1041240032670961922, which contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 721539979 and 721540006.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (721540037) 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 7 ways as a sum of consecutive naturals, for example, 241376 + ... + 244346.

It is an arithmetic number, because the mean of its divisors is an integer number (90729216).

Almost surely, 2^721540031 is an apocalyptic number.

721540031 is a deficient number, since it is larger than the sum of its proper divisors (4293697).

721540031 is a wasteful number, since it uses less digits than its factorization.

721540031 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4333.

The product of its (nonzero) digits is 840, while the sum is 23.

The square root of 721540031 is about 26861.4971846321. The cubic root of 721540031 is about 896.9195222242.

Adding to 721540031 its reverse (130045127), we get a palindrome (851585158).

The spelling of 721540031 in words is "seven hundred twenty-one million, five hundred forty thousand, thirty-one".