720631 has 4 divisors (see below), whose sum is σ = 726264. Its totient is φ = 715000.

The previous prime is 720619. The next prime is 720653. The reversal of 720631 is 136027.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-720631 is a prime.

It is a super-2 number, since 2×720631² = 1038618076322, which contains 22 as substring.

720631 is a lucky number.

It is a junction number, because it is equal to n+sod(n) for n = 720599 and 720608.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (720611) 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, 2620 + ... + 2881.

It is an arithmetic number, because the mean of its divisors is an integer number (181566).

2⁷²⁰⁶³¹ is an apocalyptic number.

720631 is a deficient number, since it is larger than the sum of its proper divisors (5633).

720631 is a wasteful number, since it uses less digits than its factorization.

720631 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5632.

The product of its (nonzero) digits is 252, while the sum is 19.

The square root of 720631 is about 848.8998763105. The cubic root of 720631 is about 89.6542703082.

Adding to 720631 its reverse (136027), we get a palindrome (856658).

The spelling of 720631 in words is "seven hundred twenty thousand, six hundred thirty-one".