138897540 has 36 divisors (see below), whose sum is σ = 421323084. Its totient is φ = 37039296.

The previous prime is 138897533. The next prime is 138897541. The reversal of 138897540 is 45798831.

138897540 is a `hidden beast` number, since 13 + 8 + 8 + 97 + 540 = 666.

It can be written as a sum of positive squares in 2 ways, for example, as 35712576 + 103184964 = 5976^2 + 10158^2 .

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 (45).

It is not an unprimeable number, because it can be changed into a prime (138897541) 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, 385647 + ... + 386006.

It is an arithmetic number, because the mean of its divisors is an integer number (11703419).

Almost surely, 2^138897540 is an apocalyptic number.

138897540 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

138897540 is an abundant number, since it is smaller than the sum of its proper divisors (282425544).

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

138897540 is a wasteful number, since it uses less digits than its factorization.

138897540 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 771668 (or 771663 counting only the distinct ones).

The product of its (nonzero) digits is 241920, while the sum is 45.

The square root of 138897540 is about 11785.4800496204. The cubic root of 138897540 is about 517.8828365079.

The spelling of 138897540 in words is "one hundred thirty-eight million, eight hundred ninety-seven thousand, five hundred forty".