138909797 has 16 divisors (see below), whose sum is σ = 155526000. Its totient is φ = 123185664.

The previous prime is 138909781. The next prime is 138909809. The reversal of 138909797 is 797909831.

It is a Cunningham number, because it is equal to 11786²+1.

It can be written as a sum of positive squares in 8 ways, for example, as 20557156 + 118352641 = 4534^2 + 10879^2 .

It is a cyclic number.

It is not a de Polignac number, because 138909797 - 2⁴ = 138909781 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (138939797) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 85529 + ... + 87137.

It is an arithmetic number, because the mean of its divisors is an integer number (9720375).

Almost surely, 2^138909797 is an apocalyptic number.

It is an amenable number.

138909797 is a deficient number, since it is larger than the sum of its proper divisors (16616203).

138909797 is a wasteful number, since it uses less digits than its factorization.

138909797 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1880.

The product of its (nonzero) digits is 857304, while the sum is 53.

The square root of 138909797 is about 11786.0000424232. Note that the first 4 decimals coincide. The cubic root of 138909797 is about 517.8980695668.

The spelling of 138909797 in words is "one hundred thirty-eight million, nine hundred nine thousand, seven hundred ninety-seven".