1664351616 has 64 divisors (see below), whose sum is σ = 4462361280. Its totient is φ = 549585408.

The previous prime is 1664351609. The next prime is 1664351617. The reversal of 1664351616 is 6161534661.

It is a tau number, because it is divible by the number of its divisors (64).

It is a super-2 number, since 2×1664351616² = 5540132603363622912, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1664351617) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 20835 + ... + 61341.

It is an arithmetic number, because the mean of its divisors is an integer number (69724395).

Almost surely, 2^1664351616 is an apocalyptic number.

1664351616 is a gapful number since it is divisible by the number (16) 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 1664351616, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2231180640).

1664351616 is an abundant number, since it is smaller than the sum of its proper divisors (2798009664).

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

1664351616 is a wasteful number, since it uses less digits than its factorization.

1664351616 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 40631 (or 40619 counting only the distinct ones).

The product of its digits is 77760, while the sum is 39.

The square root of 1664351616 is about 40796.4657292761. The cubic root of 1664351616 is about 1185.0818879123.

The spelling of 1664351616 in words is "one billion, six hundred sixty-four million, three hundred fifty-one thousand, six hundred sixteen".