21806061 has 16 divisors (see below), whose sum is σ = 30081408. Its totient is φ = 14040000.

The previous prime is 21806041. The next prime is 21806063. The reversal of 21806061 is 16060812.

It is not a de Polignac number, because 21806061 - 2⁶ = 21805997 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21806063) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 16111 + ... + 17411.

It is an arithmetic number, because the mean of its divisors is an integer number (1880088).

Almost surely, 2^21806061 is an apocalyptic number.

It is an amenable number.

21806061 is a deficient number, since it is larger than the sum of its proper divisors (8275347).

21806061 is a wasteful number, since it uses less digits than its factorization.

21806061 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1492.

The product of its (nonzero) digits is 576, while the sum is 24.

The square root of 21806061 is about 4669.6960286511. The cubic root of 21806061 is about 279.3781309300.

Adding to 21806061 its reverse (16060812), we get a palindrome (37866873).

The spelling of 21806061 in words is "twenty-one million, eight hundred six thousand, sixty-one".