661138272 has 36 divisors (see below), whose sum is σ = 1880112780. Its totient is φ = 220379328.

The previous prime is 661138241. The next prime is 661138273. The reversal of 661138272 is 272831166.

661138272 is a `hidden beast` number, since 6 + 611 + 38 + 2 + 7 + 2 = 666.

It is a tau number, because it is divible by the number of its divisors (36).

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (661138273) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 1147522 + ... + 1148097.

It is an arithmetic number, because the mean of its divisors is an integer number (52225355).

Almost surely, 2^661138272 is an apocalyptic number.

It is an amenable number.

661138272 is an abundant number, since it is smaller than the sum of its proper divisors (1218974508).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

661138272 is a wasteful number, since it uses less digits than its factorization.

661138272 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2295635 (or 2295624 counting only the distinct ones).

The product of its digits is 24192, while the sum is 36.

The square root of 661138272 is about 25712.6092024905. The cubic root of 661138272 is about 871.1590101810.

The spelling of 661138272 in words is "six hundred sixty-one million, one hundred thirty-eight thousand, two hundred seventy-two".