138387737721 has 16 divisors (see below), whose sum is σ = 186505971840. Its totient is φ = 91265587200.

The previous prime is 138387737713. The next prime is 138387737729. The reversal of 138387737721 is 127737783831.

It is an interprime number because it is at equal distance from previous prime (138387737713) and next prime (138387737729).

It is not a de Polignac number, because 138387737721 - 2³ = 138387737713 is a prime.

It is not an unprimeable number, because it can be changed into a prime (138387737729) 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, 151300 + ... + 547418.

It is an arithmetic number, because the mean of its divisors is an integer number (11656623240).

Almost surely, 2^138387737721 is an apocalyptic number.

It is an amenable number.

138387737721 is a deficient number, since it is larger than the sum of its proper divisors (48118234119).

138387737721 is a wasteful number, since it uses less digits than its factorization.

138387737721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 397376.

The product of its digits is 8297856, while the sum is 57.

The spelling of 138387737721 in words is "one hundred thirty-eight billion, three hundred eighty-seven million, seven hundred thirty-seven thousand, seven hundred twenty-one".