645524401 has 4 divisors (see below), whose sum is σ = 647855092. Its totient is φ = 643193712.

The previous prime is 645524339. The next prime is 645524413. The reversal of 645524401 is 104425546.

It is a happy number.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 122213025 + 523311376 = 11055^2 + 22876^2 .

It is a cyclic number.

It is not a de Polignac number, because 645524401 - 2¹⁵ = 645491633 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (645524441) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1164930 + ... + 1165483.

It is an arithmetic number, because the mean of its divisors is an integer number (161963773).

Almost surely, 2^645524401 is an apocalyptic number.

It is an amenable number.

645524401 is a deficient number, since it is larger than the sum of its proper divisors (2330691).

645524401 is a wasteful number, since it uses less digits than its factorization.

645524401 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2330690.

The product of its (nonzero) digits is 19200, while the sum is 31.

The square root of 645524401 is about 25407.1722354142. The cubic root of 645524401 is about 864.2463508087.

Adding to 645524401 its reverse (104425546), we get a palindrome (749949947).

The spelling of 645524401 in words is "six hundred forty-five million, five hundred twenty-four thousand, four hundred one".