1640257581 has 16 divisors (see below), whose sum is σ = 2290544640. Its totient is φ = 1042089840.

The previous prime is 1640257579. The next prime is 1640257589. The reversal of 1640257581 is 1857520461.

It is not a de Polignac number, because 1640257581 - 2¹ = 1640257579 is a prime.

It is a super-2 number, since 2×1640257581² = 5380889864055943122, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1640257589) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 25161 + ... + 62558.

It is an arithmetic number, because the mean of its divisors is an integer number (143159040).

Almost surely, 2^1640257581 is an apocalyptic number.

It is an amenable number.

1640257581 is a deficient number, since it is larger than the sum of its proper divisors (650287059).

1640257581 is a wasteful number, since it uses less digits than its factorization.

1640257581 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 88016.

The product of its (nonzero) digits is 67200, while the sum is 39.

The square root of 1640257581 is about 40500.0935924844. The cubic root of 1640257581 is about 1179.3354442948.

The spelling of 1640257581 in words is "one billion, six hundred forty million, two hundred fifty-seven thousand, five hundred eighty-one".