720981 has 28 divisors (see below), whose sum is σ = 1154208. Its totient is φ = 449064.

The previous prime is 720971. The next prime is 720983. The reversal of 720981 is 189027.

It is a de Polignac number, because none of the positive numbers 2^k-720981 is a prime.

It is a super-2 number, since 2×720981² = 1039627204722, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (720983) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 27 ways as a sum of consecutive naturals, for example, 16746 + ... + 16788.

2⁷²⁰⁹⁸¹ is an apocalyptic number.

It is an amenable number.

720981 is a deficient number, since it is larger than the sum of its proper divisors (433227).

720981 is an equidigital number, since it uses as much as digits as its factorization.

720981 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 84 (or 69 counting only the distinct ones).

The product of its (nonzero) digits is 1008, while the sum is 27.

The square root of 720981 is about 849.1060004499. The cubic root of 720981 is about 89.6687825509.

The spelling of 720981 in words is "seven hundred twenty thousand, nine hundred eighty-one".