138881556 has 36 divisors (see below), whose sum is σ = 382977504. Its totient is φ = 42085200.

The previous prime is 138881531. The next prime is 138881557. The reversal of 138881556 is 655188831.

138881556 is a `hidden beast` number, since 13 + 8 + 8 + 81 + 556 = 666.

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

It is a super-2 number, since 2×138881556² = 38576173193962272, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (138881557) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 174960 + ... + 175751.

It is an arithmetic number, because the mean of its divisors is an integer number (10638264).

Almost surely, 2^138881556 is an apocalyptic number.

It is an amenable number.

138881556 is an abundant number, since it is smaller than the sum of its proper divisors (244095948).

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

138881556 is a wasteful number, since it uses less digits than its factorization.

138881556 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 350732 (or 350727 counting only the distinct ones).

The product of its digits is 230400, while the sum is 45.

The square root of 138881556 is about 11784.8019075418. The cubic root of 138881556 is about 517.8629701690.

It can be divided in two parts, 1388 and 81556, that added together give a square (82944 = 288²).

The spelling of 138881556 in words is "one hundred thirty-eight million, eight hundred eighty-one thousand, five hundred fifty-six".