645469234921 has 9 divisors (see below), whose sum is σ = 750858509271. Its totient is φ = 553254523752.

The previous prime is 645469234901. The next prime is 645469234957. The reversal of 645469234921 is 129432964546.

The square root of 645469234921 is 803411.

It is a perfect power (a square), and thus also a powerful number.

It can be written as a sum of positive squares in only one way, i.e., 633623960025 + 11845274896 = 796005^2 + 108836^2 .

It is not a de Polignac number, because 645469234921 - 2⁵ = 645469234889 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (645469234901) by changing a digit.

It is a polite number, since it can be written in 8 ways as a sum of consecutive naturals, for example, 5566491 + ... + 5681263.

Almost surely, 2^645469234921 is an apocalyptic number.

645469234921 is the 803411-st square number.

645469234921 is the 401706-th centered octagonal number.

It is an amenable number.

645469234921 is a deficient number, since it is larger than the sum of its proper divisors (105389274350).

645469234921 is an frugal number, since it uses more digits than its factorization.

645469234921 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 229560 (or 114780 counting only the distinct ones).

The product of its digits is 11197440, while the sum is 55.

The spelling of 645469234921 in words is "six hundred forty-five billion, four hundred sixty-nine million, two hundred thirty-four thousand, nine hundred twenty-one".