2721605 has 8 divisors (see below), whose sum is σ = 3295512. Its totient is φ = 2157568.

The previous prime is 2721577. The next prime is 2721619. The reversal of 2721605 is 5061272.

It can be written as a sum of positive squares in 4 ways, for example, as 158404 + 2563201 = 398^2 + 1601^2 .

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

It is a cyclic number.

It is not a de Polignac number, because 2721605 - 2¹² = 2717509 is a prime.

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1844 + ... + 2973.

It is an arithmetic number, because the mean of its divisors is an integer number (411939).

2^2721605 is an apocalyptic number.

It is an amenable number.

2721605 is a deficient number, since it is larger than the sum of its proper divisors (573907).

2721605 is a wasteful number, since it uses less digits than its factorization.

2721605 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4935.

The product of its (nonzero) digits is 840, while the sum is 23.

The square root of 2721605 is about 1649.7287655854. The cubic root of 2721605 is about 139.6180917869.

Adding to 2721605 its reverse (5061272), we get a palindrome (7782877).

It can be divided in two parts, 2721 and 605, that multiplied together give a triangular number (1646205 = T₁₈₁₄).

The spelling of 2721605 in words is "two million, seven hundred twenty-one thousand, six hundred five".