138302721 has 24 divisors (see below), whose sum is σ = 207733344. Its totient is φ = 91951200.

The previous prime is 138302699. The next prime is 138302741. The reversal of 138302721 is 127203831.

It is not a de Polignac number, because 138302721 - 2⁹ = 138302209 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is not an unprimeable number, because it can be changed into a prime (138302741) 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 23 ways as a sum of consecutive naturals, for example, 145570 + ... + 146516.

It is an arithmetic number, because the mean of its divisors is an integer number (8655556).

Almost surely, 2^138302721 is an apocalyptic number.

It is an amenable number.

138302721 is a deficient number, since it is larger than the sum of its proper divisors (69430623).

138302721 is an frugal number, since it uses more digits than its factorization.

138302721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1563 (or 1551 counting only the distinct ones).

The product of its (nonzero) digits is 2016, while the sum is 27.

The square root of 138302721 is about 11760.2177275763. The cubic root of 138302721 is about 517.1425130307.

The spelling of 138302721 in words is "one hundred thirty-eight million, three hundred two thousand, seven hundred twenty-one".