2721861 has 6 divisors (see below), whose sum is σ = 3931590. Its totient is φ = 1814568.

The previous prime is 2721841. The next prime is 2721863. The reversal of 2721861 is 1681272.

It can be written as a sum of positive squares in only one way, i.e., 2461761 + 260100 = 1569^2 + 510^2 .

It is not a de Polignac number, because 2721861 - 2²¹ = 624709 is a prime.

2721861 is a lucky number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (2721863) 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, 151206 + ... + 151223.

It is an arithmetic number, because the mean of its divisors is an integer number (655265).

2^2721861 is an apocalyptic number.

It is an amenable number.

2721861 is a deficient number, since it is larger than the sum of its proper divisors (1209729).

2721861 is a wasteful number, since it uses less digits than its factorization.

2721861 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 302435 (or 302432 counting only the distinct ones).

The product of its digits is 1344, while the sum is 27.

The square root of 2721861 is about 1649.8063522729. The cubic root of 2721861 is about 139.6224692420.

The spelling of 2721861 in words is "two million, seven hundred twenty-one thousand, eight hundred sixty-one".