661533938 has 18 divisors (see below), whose sum is σ = 1075271949. Its totient is φ = 305105112.

The previous prime is 661533931. The next prime is 661533949. The reversal of 661533938 is 839335166.

It can be written as a sum of positive squares in 2 ways, for example, as 565631089 + 95902849 = 23783^2 + 9793^2 .

It is an ABA number since it can be written as A⋅B^A, here for A=2, B=18187.

It is a super-2 number, since 2×661533938² = 875254302251575688, which contains 22 as substring.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (661533931) 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 8 ways as a sum of consecutive naturals, for example, 472163 + ... + 473561.

Almost surely, 2^661533938 is an apocalyptic number.

661533938 is a deficient number, since it is larger than the sum of its proper divisors (413738011).

661533938 is an equidigital number, since it uses as much as digits as its factorization.

661533938 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2826 (or 1414 counting only the distinct ones).

The product of its digits is 349920, while the sum is 44.

The square root of 661533938 is about 25720.3020588795. The cubic root of 661533938 is about 871.3327606543.

The spelling of 661533938 in words is "six hundred sixty-one million, five hundred thirty-three thousand, nine hundred thirty-eight".