1021621 has 2 divisors, whose sum is σ = 1021622. Its totient is φ = 1021620.

The previous prime is 1021577. The next prime is 1021627. The reversal of 1021621 is 1261201.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 1020100 + 1521 = 1010^2 + 39^2 .

It is a cyclic number.

It is not a de Polignac number, because 1021621 - 2¹³ = 1013429 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1021627) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 510810 + 510811.

It is an arithmetic number, because the mean of its divisors is an integer number (510811).

2^1021621 is an apocalyptic number.

It is an amenable number.

1021621 is a deficient number, since it is larger than the sum of its proper divisors (1).

1021621 is an equidigital number, since it uses as much as digits as its factorization.

1021621 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 24, while the sum is 13.

The square root of 1021621 is about 1010.7526898307. The cubic root of 1021621 is about 100.7155674195.

Adding to 1021621 its reverse (1261201), we get a palindrome (2282822).

The spelling of 1021621 in words is "one million, twenty-one thousand, six hundred twenty-one".