1525821681 has 4 divisors (see below), whose sum is σ = 2034428912. Its totient is φ = 1017214452.

The previous prime is 1525821667. The next prime is 1525821701. The reversal of 1525821681 is 1861285251.

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 not a de Polignac number, because 1525821681 - 2¹⁹ = 1525297393 is a prime.

It is a super-2 number, since 2×1525821681² = 4656263604419331522, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1525821881) 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, 254303611 + ... + 254303616.

It is an arithmetic number, because the mean of its divisors is an integer number (508607228).

Almost surely, 2^1525821681 is an apocalyptic number.

It is an amenable number.

1525821681 is a deficient number, since it is larger than the sum of its proper divisors (508607231).

1525821681 is an equidigital number, since it uses as much as digits as its factorization.

1525821681 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 508607230.

The product of its digits is 38400, while the sum is 39.

The square root of 1525821681 is about 39061.7675099323. The cubic root of 1525821681 is about 1151.2454511922.

The spelling of 1525821681 in words is "one billion, five hundred twenty-five million, eight hundred twenty-one thousand, six hundred eighty-one".