1604261521 has 4 divisors (see below), whose sum is σ = 1605881344. Its totient is φ = 1602641700.

The previous prime is 1604261513. The next prime is 1604261537. The reversal of 1604261521 is 1251624061.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 1604261521 - 2³ = 1604261513 is a prime.

It is a super-2 number, since 2×1604261521² = 5147310055522466882, which contains 22 as substring.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 1604261521.

It is not an unprimeable number, because it can be changed into a prime (1604261221) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 808425 + ... + 810406.

It is an arithmetic number, because the mean of its divisors is an integer number (401470336).

Almost surely, 2^1604261521 is an apocalyptic number.

It is an amenable number.

1604261521 is a deficient number, since it is larger than the sum of its proper divisors (1619823).

1604261521 is an equidigital number, since it uses as much as digits as its factorization.

1604261521 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1619822.

The product of its (nonzero) digits is 2880, while the sum is 28.

The square root of 1604261521 is about 40053.2335898114. The cubic root of 1604261521 is about 1170.6445716569.

Adding to 1604261521 its reverse (1251624061), we get a palindrome (2855885582).

The spelling of 1604261521 in words is "one billion, six hundred four million, two hundred sixty-one thousand, five hundred twenty-one".