2721621 has 32 divisors (see below), whose sum is σ = 4435200. Its totient is φ = 1451520.

The previous prime is 2721619. The next prime is 2721671. The reversal of 2721621 is 1261272.

2721621 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is not a de Polignac number, because 2721621 - 2¹ = 2721619 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (21).

2721621 is a lucky number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (2721671) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 24915 + ... + 25023.

It is an arithmetic number, because the mean of its divisors is an integer number (138600).

2^2721621 is an apocalyptic number.

2721621 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

It is an amenable number.

2721621 is a deficient number, since it is larger than the sum of its proper divisors (1713579).

2721621 is a wasteful number, since it uses less digits than its factorization.

2721621 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 189.

The product of its digits is 336, while the sum is 21.

The square root of 2721621 is about 1649.7336148603. The cubic root of 2721621 is about 139.6183653859.

Adding to 2721621 its reverse (1261272), we get a palindrome (3982893).

It can be divided in two parts, 27216 and 21, that multiplied together give a square (571536 = 756²).

The spelling of 2721621 in words is "two million, seven hundred twenty-one thousand, six hundred twenty-one".