660416021 has 4 divisors (see below), whose sum is σ = 661740000. Its totient is φ = 659092044.

The previous prime is 660415999. The next prime is 660416047. The reversal of 660416021 is 120614066.

It is a happy number.

660416021 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 120614066 = 2 ⋅60307033.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-660416021 is a prime.

It is a super-2 number, since 2×660416021² = 872298641586944882, which contains 22 as substring.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (660416921) 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, 661241 + ... + 662238.

It is an arithmetic number, because the mean of its divisors is an integer number (165435000).

Almost surely, 2^660416021 is an apocalyptic number.

It is an amenable number.

660416021 is a deficient number, since it is larger than the sum of its proper divisors (1323979).

660416021 is a wasteful number, since it uses less digits than its factorization.

660416021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1323978.

The product of its (nonzero) digits is 1728, while the sum is 26.

The square root of 660416021 is about 25698.5606795400. The cubic root of 660416021 is about 870.8416662150.

The spelling of 660416021 in words is "six hundred sixty million, four hundred sixteen thousand, twenty-one".