720281661 has 12 divisors (see below), whose sum is σ = 1055619936. Its totient is φ = 436534120.

The previous prime is 720281657. The next prime is 720281677. The reversal of 720281661 is 166182027.

It is not a de Polignac number, because 720281661 - 2² = 720281657 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (33).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (720281641) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 991761 + ... + 992486.

It is an arithmetic number, because the mean of its divisors is an integer number (87968328).

Almost surely, 2^720281661 is an apocalyptic number.

It is an amenable number.

720281661 is a deficient number, since it is larger than the sum of its proper divisors (335338275).

720281661 is a wasteful number, since it uses less digits than its factorization.

720281661 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1984272 (or 1984261 counting only the distinct ones).

The product of its (nonzero) digits is 8064, while the sum is 33.

The square root of 720281661 is about 26838.0636596607. The cubic root of 720281661 is about 896.3978078655.

The spelling of 720281661 in words is "seven hundred twenty million, two hundred eighty-one thousand, six hundred sixty-one".