138951921 has 16 divisors (see below), whose sum is σ = 195897600. Its totient is φ = 87364368.

The previous prime is 138951913. The next prime is 138951941. The reversal of 138951921 is 129159831.

It is not a de Polignac number, because 138951921 - 2³ = 138951913 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 138951921.

It is not an unprimeable number, because it can be changed into a prime (138951941) 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, 7570 + ... + 18308.

It is an arithmetic number, because the mean of its divisors is an integer number (12243600).

Almost surely, 2^138951921 is an apocalyptic number.

It is an amenable number.

138951921 is a deficient number, since it is larger than the sum of its proper divisors (56945679).

138951921 is a wasteful number, since it uses less digits than its factorization.

138951921 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10988.

The product of its digits is 19440, while the sum is 39.

The square root of 138951921 is about 11787.7869424248. The cubic root of 138951921 is about 517.9504146471.

The spelling of 138951921 in words is "one hundred thirty-eight million, nine hundred fifty-one thousand, nine hundred twenty-one".