280320021 has 80 divisors (see below), whose sum is σ = 474211584. Its totient is φ = 164077056.

The previous prime is 280320017. The next prime is 280320037. The reversal of 280320021 is 120023082.

It is a happy number.

It is not a de Polignac number, because 280320021 - 2² = 280320017 is a prime.

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 280319976 and 280320003.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (280320721) by changing a digit.

It is a polite number, since it can be written in 79 ways as a sum of consecutive naturals, for example, 1678480 + ... + 1678646.

Almost surely, 2^280320021 is an apocalyptic number.

It is an amenable number.

280320021 is a deficient number, since it is larger than the sum of its proper divisors (193891563).

280320021 is a wasteful number, since it uses less digits than its factorization.

280320021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 272 (or 263 counting only the distinct ones).

The product of its (nonzero) digits is 192, while the sum is 18.

The square root of 280320021 is about 16742.7602563018. The cubic root of 280320021 is about 654.4624075981.

It can be divided in two parts, 2803200 and 21, that added together give a cube (2803221 = 141³).

The spelling of 280320021 in words is "two hundred eighty million, three hundred twenty thousand, twenty-one".