138531977 has 2 divisors, whose sum is σ = 138531978. Its totient is φ = 138531976.

The previous prime is 138531931. The next prime is 138532001. The reversal of 138531977 is 779135831.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 108764041 + 29767936 = 10429^2 + 5456^2 .

It is a cyclic number.

It is not a de Polignac number, because 138531977 - 2²² = 134337673 is a prime.

It is a super-2 number, since 2×138531977² = 38382217303057058, which contains 22 as substring.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (138531917) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 69265988 + 69265989.

It is an arithmetic number, because the mean of its divisors is an integer number (69265989).

Almost surely, 2^138531977 is an apocalyptic number.

It is an amenable number.

138531977 is a deficient number, since it is larger than the sum of its proper divisors (1).

138531977 is an equidigital number, since it uses as much as digits as its factorization.

138531977 is an evil number, because the sum of its binary digits is even.

The product of its digits is 158760, while the sum is 44.

The square root of 138531977 is about 11769.9607900791. The cubic root of 138531977 is about 517.4281005076.

The spelling of 138531977 in words is "one hundred thirty-eight million, five hundred thirty-one thousand, nine hundred seventy-seven".