138402491 has 8 divisors (see below), whose sum is σ = 146678544. Its totient is φ = 130141440.

The previous prime is 138402461. The next prime is 138402493. The reversal of 138402491 is 194204831.

It is a happy number.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 138402491 - 2⁶ = 138402427 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (138402493) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 19376 + ... + 25538.

It is an arithmetic number, because the mean of its divisors is an integer number (18334818).

Almost surely, 2^138402491 is an apocalyptic number.

138402491 is a deficient number, since it is larger than the sum of its proper divisors (8276053).

138402491 is a wasteful number, since it uses less digits than its factorization.

138402491 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7501.

The product of its (nonzero) digits is 6912, while the sum is 32.

The square root of 138402491 is about 11764.4588060820. The cubic root of 138402491 is about 517.2668367036.

The spelling of 138402491 in words is "one hundred thirty-eight million, four hundred two thousand, four hundred ninety-one".