138215661 has 8 divisors (see below), whose sum is σ = 195128064. Its totient is φ = 86723520.

The previous prime is 138215657. The next prime is 138215681. The reversal of 138215661 is 166512831.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 138215661 - 2² = 138215657 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (138215621) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1355005 + ... + 1355106.

It is an arithmetic number, because the mean of its divisors is an integer number (24391008).

Almost surely, 2^138215661 is an apocalyptic number.

It is an amenable number.

138215661 is a deficient number, since it is larger than the sum of its proper divisors (56912403).

138215661 is a wasteful number, since it uses less digits than its factorization.

138215661 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2710131.

The product of its digits is 8640, while the sum is 33.

The square root of 138215661 is about 11756.5156828033. The cubic root of 138215661 is about 517.0339784644.

The spelling of 138215661 in words is "one hundred thirty-eight million, two hundred fifteen thousand, six hundred sixty-one".