1521681 has 8 divisors (see below), whose sum is σ = 2318784. Its totient is φ = 869520.

The previous prime is 1521677. The next prime is 1521731. The reversal of 1521681 is 1861251.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 1521681 - 2² = 1521677 is a prime.

It is a super-2 number, since 2×1521681² = 4631026131522, which contains 22 as substring.

1521681 is a lucky number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1521671) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 36210 + ... + 36251.

It is an arithmetic number, because the mean of its divisors is an integer number (289848).

2^1521681 is an apocalyptic number.

It is an amenable number.

1521681 is a deficient number, since it is larger than the sum of its proper divisors (797103).

1521681 is an equidigital number, since it uses as much as digits as its factorization.

1521681 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 72471.

The product of its digits is 480, while the sum is 24.

The square root of 1521681 is about 1233.5643477338. The cubic root of 1521681 is about 115.0203114722.

The spelling of 1521681 in words is "one million, five hundred twenty-one thousand, six hundred eighty-one".