1604656581 has 16 divisors (see below), whose sum is σ = 2366022720. Its totient is φ = 959195520.

The previous prime is 1604656541. The next prime is 1604656591. The reversal of 1604656581 is 1856564061.

It is not a de Polignac number, because 1604656581 - 2⁶ = 1604656517 is a prime.

It is a super-2 number, since 2×1604656581² = 5149845485893219122, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1604656511) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 330646 + ... + 335463.

It is an arithmetic number, because the mean of its divisors is an integer number (147876420).

Almost surely, 2^1604656581 is an apocalyptic number.

1604656581 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

It is an amenable number.

1604656581 is a deficient number, since it is larger than the sum of its proper divisors (761366139).

1604656581 is a wasteful number, since it uses less digits than its factorization.

1604656581 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 666196.

The product of its (nonzero) digits is 172800, while the sum is 42.

The square root of 1604656581 is about 40058.1649729490. The cubic root of 1604656581 is about 1170.7406567571.

It can be divided in two parts, 16046 and 56581, that added together give a palindrome (72627).

The spelling of 1604656581 in words is "one billion, six hundred four million, six hundred fifty-six thousand, five hundred eighty-one".