661237885 has 16 divisors (see below), whose sum is σ = 989281152. Its totient is φ = 412200000.

The previous prime is 661237883. The next prime is 661237901. The reversal of 661237885 is 588732166.

It is not a de Polignac number, because 661237885 - 2¹ = 661237883 is a prime.

It is a super-3 number, since 3×661237885³ (a number of 27 digits) contains 333 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (661237883) 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 15 ways as a sum of consecutive naturals, for example, 858366 + ... + 859135.

It is an arithmetic number, because the mean of its divisors is an integer number (61830072).

Almost surely, 2^661237885 is an apocalyptic number.

It is an amenable number.

661237885 is a deficient number, since it is larger than the sum of its proper divisors (328043267).

661237885 is a wasteful number, since it uses less digits than its factorization.

661237885 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1717524.

The product of its digits is 483840, while the sum is 46.

The square root of 661237885 is about 25714.5461752682. The cubic root of 661237885 is about 871.2027601842.

It can be divided in two parts, 66 and 1237885, that added together give a triangular number (1237951 = T₁₅₇₃).

The spelling of 661237885 in words is "six hundred sixty-one million, two hundred thirty-seven thousand, eight hundred eighty-five".