21722661 has 40 divisors (see below), whose sum is σ = 34476288. Its totient is φ = 13608000.

The previous prime is 21722647. The next prime is 21722671. The reversal of 21722661 is 16622712.

It is not a de Polignac number, because 21722661 - 2⁵ = 21722629 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21722671) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 39 ways as a sum of consecutive naturals, for example, 102846 + ... + 103056.

Almost surely, 2^21722661 is an apocalyptic number.

It is an amenable number.

21722661 is a deficient number, since it is larger than the sum of its proper divisors (12753627).

21722661 is a wasteful number, since it uses less digits than its factorization.

21722661 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 295 (or 286 counting only the distinct ones).

The product of its digits is 2016, while the sum is 27.

The square root of 21722661 is about 4660.7575564494. The cubic root of 21722661 is about 279.0215037189.

The spelling of 21722661 in words is "twenty-one million, seven hundred twenty-two thousand, six hundred sixty-one".