5721661 has 4 divisors (see below), whose sum is σ = 6241824. Its totient is φ = 5201500.

The previous prime is 5721659. The next prime is 5721689. The reversal of 5721661 is 1661275.

5721661 is digitally balanced in base 3, because in such base it contains all the possibile digits an equal number of times.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 5721661 - 2¹ = 5721659 is a prime.

It is a Duffinian number.

5721661 is a lucky number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (5721601) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 260065 + ... + 260086.

It is an arithmetic number, because the mean of its divisors is an integer number (1560456).

Almost surely, 2^5721661 is an apocalyptic number.

It is an amenable number.

5721661 is a deficient number, since it is larger than the sum of its proper divisors (520163).

5721661 is a wasteful number, since it uses less digits than its factorization.

5721661 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 520162.

The product of its digits is 2520, while the sum is 28.

The square root of 5721661 is about 2391.9993729096. Note that the first 3 decimals coincide. The cubic root of 5721661 is about 178.8575898815.

The spelling of 5721661 in words is "five million, seven hundred twenty-one thousand, six hundred sixty-one".