511331661 has 12 divisors (see below), whose sum is σ = 782036892. Its totient is φ = 320835456.

The previous prime is 511331617. The next prime is 511331671. The reversal of 511331661 is 166133115.

It can be written as a sum of positive squares in 2 ways, for example, as 142922025 + 368409636 = 11955^2 + 19194^2 .

It is not a de Polignac number, because 511331661 - 2¹¹ = 511329613 is a prime.

It is a super-2 number, since 2×511331661² = 522920135082037842, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (511331671) 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 11 ways as a sum of consecutive naturals, for example, 1670866 + ... + 1671171.

It is an arithmetic number, because the mean of its divisors is an integer number (65169741).

Almost surely, 2^511331661 is an apocalyptic number.

511331661 is a gapful number since it is divisible by the number (51) formed by its first and last digit.

It is an amenable number.

511331661 is a deficient number, since it is larger than the sum of its proper divisors (270705231).

511331661 is a wasteful number, since it uses less digits than its factorization.

511331661 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3342060 (or 3342057 counting only the distinct ones).

The product of its digits is 1620, while the sum is 27.

The square root of 511331661 is about 22612.6438303883. The cubic root of 511331661 is about 799.6517551998.

Adding to 511331661 its reverse (166133115), we get a palindrome (677464776).

The spelling of 511331661 in words is "five hundred eleven million, three hundred thirty-one thousand, six hundred sixty-one".