1645521647 has 32 divisors (see below), whose sum is σ = 2183500800. Its totient is φ = 1200545280.

The previous prime is 1645521643. The next prime is 1645521679. The reversal of 1645521647 is 7461255461.

It is not a de Polignac number, because 1645521647 - 2² = 1645521643 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 (1645521643) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 257333 + ... + 263649.

It is an arithmetic number, because the mean of its divisors is an integer number (68234400).

Almost surely, 2^1645521647 is an apocalyptic number.

1645521647 is a gapful number since it is divisible by the number (17) formed by its first and last digit.

1645521647 is a deficient number, since it is larger than the sum of its proper divisors (537979153).

1645521647 is a wasteful number, since it uses less digits than its factorization.

1645521647 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6551.

The product of its digits is 201600, while the sum is 41.

The square root of 1645521647 is about 40565.0298533108. The cubic root of 1645521647 is about 1180.5957077843.

The spelling of 1645521647 in words is "one billion, six hundred forty-five million, five hundred twenty-one thousand, six hundred forty-seven".