657138391 has 8 divisors (see below), whose sum is σ = 808785824. Its totient is φ = 519933600.

The previous prime is 657138343. The next prime is 657138409. The reversal of 657138391 is 193831756.

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 657138391 - 2¹⁵ = 657105623 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (657138301) 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, 3610560 + ... + 3610741.

It is an arithmetic number, because the mean of its divisors is an integer number (101098228).

Almost surely, 2^657138391 is an apocalyptic number.

657138391 is a deficient number, since it is larger than the sum of its proper divisors (151647433).

657138391 is a wasteful number, since it uses less digits than its factorization.

657138391 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7221321.

The product of its digits is 136080, while the sum is 43.

The square root of 657138391 is about 25634.7106673744. The cubic root of 657138391 is about 869.3986203777.

The spelling of 657138391 in words is "six hundred fifty-seven million, one hundred thirty-eight thousand, three hundred ninety-one".