657821138 has 64 divisors (see below), whose sum is σ = 1132572672. Its totient is φ = 284497920.

The previous prime is 657821089. The next prime is 657821141. The reversal of 657821138 is 831128756.

It is a Harshad number since it is a multiple of its sum of digits (41).

657821138 is a modest number, since divided by 21138 gives 6578 as remainder.

It is a junction number, because it is equal to n+sod(n) for n = 657821095 and 657821104.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 5179631 + ... + 5179757.

It is an arithmetic number, because the mean of its divisors is an integer number (17696448).

Almost surely, 2^657821138 is an apocalyptic number.

657821138 is a deficient number, since it is larger than the sum of its proper divisors (474751534).

657821138 is a wasteful number, since it uses less digits than its factorization.

657821138 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 339.

The product of its digits is 80640, while the sum is 41.

The square root of 657821138 is about 25648.0240564454. The cubic root of 657821138 is about 869.6996091578.

The spelling of 657821138 in words is "six hundred fifty-seven million, eight hundred twenty-one thousand, one hundred thirty-eight".