138891481 has 2 divisors, whose sum is σ = 138891482. Its totient is φ = 138891480.

The previous prime is 138891443. The next prime is 138891491. The reversal of 138891481 is 184198831.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 137851081 + 1040400 = 11741^2 + 1020^2 .

It is an emirp because it is prime and its reverse (184198831) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 138891481 - 2¹³ = 138883289 is a prime.

It is a super-2 number, since 2×138891481² = 38581686988746722, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (138891491) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 69445740 + 69445741.

It is an arithmetic number, because the mean of its divisors is an integer number (69445741).

Almost surely, 2^138891481 is an apocalyptic number.

It is an amenable number.

138891481 is a deficient number, since it is larger than the sum of its proper divisors (1).

138891481 is an equidigital number, since it uses as much as digits as its factorization.

138891481 is an evil number, because the sum of its binary digits is even.

The product of its digits is 55296, while the sum is 43.

The square root of 138891481 is about 11785.2229932233. Note that the first 3 decimals coincide. The cubic root of 138891481 is about 517.8753060224.

The spelling of 138891481 in words is "one hundred thirty-eight million, eight hundred ninety-one thousand, four hundred eighty-one".