646031745121 has 27 divisors (see below), whose sum is σ = 756612990099. Its totient is φ = 550004007168.

The previous prime is 646031744999. The next prime is 646031745131. The reversal of 646031745121 is 121547130646.

The square root of 646031745121 is 803761.

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., 641560950625 + 4470794496 = 800975^2 + 66864^2 .

It is not a de Polignac number, because 646031745121 - 2¹⁷ = 646031614049 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (646031745131) by changing a digit.

It is a polite number, since it can be written in 26 ways as a sum of consecutive naturals, for example, 1119638785 + ... + 1119639361.

It is an arithmetic number, because the mean of its divisors is an integer number (28022703337).

Almost surely, 2^646031745121 is an apocalyptic number.

646031745121 is the 803761-st square number.

646031745121 is the 401881-st centered octagonal number.

It is an amenable number.

646031745121 is a deficient number, since it is larger than the sum of its proper divisors (110581244978).

646031745121 is an frugal number, since it uses more digits than its factorization.

646031745121 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1566 (or 783 counting only the distinct ones).

The product of its (nonzero) digits is 120960, while the sum is 40.

Adding to 646031745121 its reverse (121547130646), we get a palindrome (767578875767).

The spelling of 646031745121 in words is "six hundred forty-six billion, thirty-one million, seven hundred forty-five thousand, one hundred twenty-one".