1664453021 has 12 divisors (see below), whose sum is σ = 2112219360. Its totient is φ = 1296975960.

The previous prime is 1664452981. The next prime is 1664453027. The reversal of 1664453021 is 1203544661.

It is a de Polignac number, because none of the positive numbers 2^k-1664453021 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 (1664453027) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 1543481 + ... + 1544558.

It is an arithmetic number, because the mean of its divisors is an integer number (176018280).

Almost surely, 2^1664453021 is an apocalyptic number.

1664453021 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

It is an amenable number.

1664453021 is a deficient number, since it is larger than the sum of its proper divisors (447766339).

1664453021 is a wasteful number, since it uses less digits than its factorization.

1664453021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3088064 (or 3088057 counting only the distinct ones).

The product of its (nonzero) digits is 17280, while the sum is 32.

The square root of 1664453021 is about 40797.7085263376. The cubic root of 1664453021 is about 1185.1059555006.

Adding to 1664453021 its reverse (1203544661), we get a palindrome (2867997682).

The spelling of 1664453021 in words is "one billion, six hundred sixty-four million, four hundred fifty-three thousand, twenty-one".