660224021 has 16 divisors (see below), whose sum is σ = 691511040. Its totient is φ = 629778240.

The previous prime is 660224011. The next prime is 660224023. The reversal of 660224021 is 120422066.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-660224021 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (660224023) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 617075 + ... + 618143.

It is an arithmetic number, because the mean of its divisors is an integer number (43219440).

Almost surely, 2^660224021 is an apocalyptic number.

It is an amenable number.

660224021 is a deficient number, since it is larger than the sum of its proper divisors (31287019).

660224021 is a wasteful number, since it uses less digits than its factorization.

660224021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1436.

The product of its (nonzero) digits is 1152, while the sum is 23.

The square root of 660224021 is about 25694.8247902180. The cubic root of 660224021 is about 870.7572659782.

Adding to 660224021 its reverse (120422066), we get a palindrome (780646087).

The spelling of 660224021 in words is "six hundred sixty million, two hundred twenty-four thousand, twenty-one".