1521621 has 6 divisors (see below), whose sum is σ = 2197910. Its totient is φ = 1014408.

The previous prime is 1521617. The next prime is 1521623. The reversal of 1521621 is 1261251.

It can be written as a sum of positive squares in only one way, i.e., 1179396 + 342225 = 1086^2 + 585^2 .

It is not a de Polignac number, because 1521621 - 2² = 1521617 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 1521594 and 1521603.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1521623) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 84526 + ... + 84543.

2^1521621 is an apocalyptic number.

It is an amenable number.

1521621 is a deficient number, since it is larger than the sum of its proper divisors (676289).

1521621 is a wasteful number, since it uses less digits than its factorization.

1521621 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 169075 (or 169072 counting only the distinct ones).

The product of its digits is 120, while the sum is 18.

The square root of 1521621 is about 1233.5400277251. The cubic root of 1521621 is about 115.0187996991.

Adding to 1521621 its reverse (1261251), we get a palindrome (2782872).

The spelling of 1521621 in words is "one million, five hundred twenty-one thousand, six hundred twenty-one".