1645021668 has 24 divisors (see below), whose sum is σ = 3840531520. Its totient is φ = 548033760.

The previous prime is 1645021601. The next prime is 1645021669. The reversal of 1645021668 is 8661205461.

It is a happy number.

It is not an unprimeable number, because it can be changed into a prime (1645021669) 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, 15463 + ... + 59406.

Almost surely, 2^1645021668 is an apocalyptic number.

It is an amenable number.

1645021668 is an abundant number, since it is smaller than the sum of its proper divisors (2195509852).

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

1645021668 is a wasteful number, since it uses less digits than its factorization.

1645021668 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 76707 (or 76705 counting only the distinct ones).

The product of its (nonzero) digits is 69120, while the sum is 39.

The square root of 1645021668 is about 40558.8667001434. The cubic root of 1645021668 is about 1180.4761240532.

The spelling of 1645021668 in words is "one billion, six hundred forty-five million, twenty-one thousand, six hundred sixty-eight".