1646665020 has 864 divisors, whose sum is σ = 7290017280. Its totient is φ = 291133440.

The previous prime is 1646664997. The next prime is 1646665063. The reversal of 1646665020 is 205666461.

It is a happy number.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 287 ways as a sum of consecutive naturals, for example, 44504442 + ... + 44504478.

It is an arithmetic number, because the mean of its divisors is an integer number (8437520).

Almost surely, 2^1646665020 is an apocalyptic number.

1646665020 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 1646665020, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (3645008640).

1646665020 is an abundant number, since it is smaller than the sum of its proper divisors (5643352260).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

1646665020 is a wasteful number, since it uses less digits than its factorization.

1646665020 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 115 (or 97 counting only the distinct ones).

The product of its (nonzero) digits is 51840, while the sum is 36.

The square root of 1646665020 is about 40579.1204931797. The cubic root of 1646665020 is about 1180.8690858817.

It can be divided in two parts, 1646 and 665020, that added together give a palindrome (666666).

The spelling of 1646665020 in words is "one billion, six hundred forty-six million, six hundred sixty-five thousand, twenty".