138209215225 has 9 divisors (see below), whose sum is σ = 171381731853. Its totient is φ = 110565885120.

The previous prime is 138209215213. The next prime is 138209215231. The reversal of 138209215225 is 522512902831.

The square root of 138209215225 is 371765.

It is a perfect power (a square), and thus also a powerful number.

It can be written as a sum of positive squares in 4 ways, for example, as 1637578089 + 136571637136 = 40467^2 + 369556^2 .

It is not a de Polignac number, because 138209215225 - 2⁹ = 138209214713 is a prime.

It is a super-2 number, since 2×138209215225² (a number of 23 digits) contains 22 as substring.

It is a Duffinian number.

It is an unprimeable number.

It is a polite number, since it can be written in 8 ways as a sum of consecutive naturals, for example, 1821649 + ... + 1896001.

Almost surely, 2^138209215225 is an apocalyptic number.

138209215225 is the 371765-th square number.

138209215225 is the 185883-rd centered octagonal number.

It is an amenable number.

138209215225 is a deficient number, since it is larger than the sum of its proper divisors (33172516628).

138209215225 is an frugal number, since it uses more digits than its factorization.

138209215225 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 148716 (or 74358 counting only the distinct ones).

The product of its (nonzero) digits is 86400, while the sum is 40.

The spelling of 138209215225 in words is "one hundred thirty-eight billion, two hundred nine million, two hundred fifteen thousand, two hundred twenty-five".