138649969 has 4 divisors (see below), whose sum is σ = 138674596. Its totient is φ = 138625344.

The previous prime is 138649963. The next prime is 138649981. The reversal of 138649969 is 969946831.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 125776225 + 12873744 = 11215^2 + 3588^2 .

It is a cyclic number.

It is not a de Polignac number, because 138649969 - 2⁹ = 138649457 is a prime.

It is a super-2 number, since 2×138649969² = 38447627807401922, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (138649963) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 757 + ... + 16669.

It is an arithmetic number, because the mean of its divisors is an integer number (34668649).

Almost surely, 2^138649969 is an apocalyptic number.

It is an amenable number.

138649969 is a deficient number, since it is larger than the sum of its proper divisors (24627).

138649969 is an equidigital number, since it uses as much as digits as its factorization.

138649969 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 24626.

The product of its digits is 2519424, while the sum is 55.

The square root of 138649969 is about 11774.9721443407. The cubic root of 138649969 is about 517.5749620302.

The spelling of 138649969 in words is "one hundred thirty-eight million, six hundred forty-nine thousand, nine hundred sixty-nine".