2101621 has 2 divisors, whose sum is σ = 2101622. Its totient is φ = 2101620.

The previous prime is 2101613. The next prime is 2101651. The reversal of 2101621 is 1261012.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1920996 + 180625 = 1386^2 + 425^2 .

It is a cyclic number.

It is not a de Polignac number, because 2101621 - 2³ = 2101613 is a prime.

It is an Ulam number.

2101621 is a lucky number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (2101651) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1050810 + 1050811.

It is an arithmetic number, because the mean of its divisors is an integer number (1050811).

2^2101621 is an apocalyptic number.

It is an amenable number.

2101621 is a deficient number, since it is larger than the sum of its proper divisors (1).

2101621 is an equidigital number, since it uses as much as digits as its factorization.

2101621 is an evil number, because the sum of its binary digits is even.

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

The square root of 2101621 is about 1449.6968648652. The cubic root of 2101621 is about 128.0908575296.

Adding to 2101621 its reverse (1261012), we get a palindrome (3362633).

The spelling of 2101621 in words is "two million, one hundred one thousand, six hundred twenty-one".