1388936991 has 32 divisors (see below), whose sum is σ = 2072770560. Its totient is φ = 821407104.

The previous prime is 1388936987. The next prime is 1388937061. The reversal of 1388936991 is 1996398831.

It is not a de Polignac number, because 1388936991 - 2² = 1388936987 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1388936981) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 249460 + ... + 254966.

It is an arithmetic number, because the mean of its divisors is an integer number (64774080).

Almost surely, 2^1388936991 is an apocalyptic number.

1388936991 is a deficient number, since it is larger than the sum of its proper divisors (683833569).

1388936991 is a wasteful number, since it uses less digits than its factorization.

1388936991 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5775.

The product of its digits is 2519424, while the sum is 57.

The square root of 1388936991 is about 37268.4449769507. Note that the first 3 decimals coincide. The cubic root of 1388936991 is about 1115.7344637768.

The spelling of 1388936991 in words is "one billion, three hundred eighty-eight million, nine hundred thirty-six thousand, nine hundred ninety-one".