645211531 has 8 divisors (see below), whose sum is σ = 649368800. Its totient is φ = 641063808.

The previous prime is 645211499. The next prime is 645211543. The reversal of 645211531 is 135112546.

645211531 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 645211531 - 2⁵ = 645211499 is a prime.

It is a super-2 number, since 2×645211531² = 832595839470727922, which contains 22 as substring.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 645211531.

It is not an unprimeable number, because it can be changed into a prime (645215531) 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, 172675 + ... + 176371.

It is an arithmetic number, because the mean of its divisors is an integer number (81171100).

Almost surely, 2^645211531 is an apocalyptic number.

645211531 is a deficient number, since it is larger than the sum of its proper divisors (4157269).

645211531 is a wasteful number, since it uses less digits than its factorization.

645211531 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4773.

The product of its digits is 3600, while the sum is 28.

The square root of 645211531 is about 25401.0143695089. The cubic root of 645211531 is about 864.1067018391.

The spelling of 645211531 in words is "six hundred forty-five million, two hundred eleven thousand, five hundred thirty-one".