21654749 has 4 divisors (see below), whose sum is σ = 21672960. Its totient is φ = 21636540.

The previous prime is 21654727. The next prime is 21654761. The reversal of 21654749 is 94745612.

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 21654749 - 2¹² = 21650653 is a prime.

It is an alternating number because its digits alternate between even and odd.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21654649) 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, 7187 + ... + 9744.

It is an arithmetic number, because the mean of its divisors is an integer number (5418240).

Almost surely, 2^21654749 is an apocalyptic number.

It is an amenable number.

21654749 is a deficient number, since it is larger than the sum of its proper divisors (18211).

21654749 is a wasteful number, since it uses less digits than its factorization.

21654749 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 18210.

The product of its digits is 60480, while the sum is 38.

The square root of 21654749 is about 4653.4663424162. The cubic root of 21654749 is about 278.7304299639.

The spelling of 21654749 in words is "twenty-one million, six hundred fifty-four thousand, seven hundred forty-nine".