257640667020826 has 4 divisors (see below), whose sum is σ = 386461000531242. Its totient is φ = 128820333510412.

The previous prime is 257640667020817. The next prime is 257640667020881. The reversal of 257640667020826 is 628020766046752.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in only one way, i.e., 230929083715201 + 26711583305625 = 15196351^2 + 5168325^2 .

It is a super-2 number, since 2×257640667020826² (a number of 30 digits) contains 22 as substring.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 64410166755205 + ... + 64410166755208.

Almost surely, 2^{257640667020826} is an apocalyptic number.

257640667020826 is a deficient number, since it is larger than the sum of its proper divisors (128820333510416).

257640667020826 is a wasteful number, since it uses less digits than its factorization.

257640667020826 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 128820333510415.

The product of its (nonzero) digits is 81285120, while the sum is 61.

The spelling of 257640667020826 in words is "two hundred fifty-seven trillion, six hundred forty billion, six hundred sixty-seven million, twenty thousand, eight hundred twenty-six".