645531611 has 4 divisors (see below), whose sum is σ = 645908424. Its totient is φ = 645154800.

The previous prime is 645531583. The next prime is 645531617. The reversal of 645531611 is 116135546.

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

It is a cyclic number.

It is not a de Polignac number, because 645531611 - 2¹⁸ = 645269467 is a prime.

It is a super-2 number, since 2×645531611² = 833422121600510642, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (645531617) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 185825 + ... + 189266.

It is an arithmetic number, because the mean of its divisors is an integer number (161477106).

Almost surely, 2^645531611 is an apocalyptic number.

645531611 is a deficient number, since it is larger than the sum of its proper divisors (376813).

645531611 is a wasteful number, since it uses less digits than its factorization.

645531611 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 376812.

The product of its digits is 10800, while the sum is 32.

The square root of 645531611 is about 25407.3141240864. The cubic root of 645531611 is about 864.2495684475.

The spelling of 645531611 in words is "six hundred forty-five million, five hundred thirty-one thousand, six hundred eleven".