21676749 has 4 divisors (see below), whose sum is σ = 28902336. Its totient is φ = 14451164.

The previous prime is 21676747. The next prime is 21676763. The reversal of 21676749 is 94767612.

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 21676749 - 2¹ = 21676747 is a prime.

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

It is a self number, because there is not a number n which added to its sum of digits gives 21676749.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21676747) 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, 3612789 + ... + 3612794.

It is an arithmetic number, because the mean of its divisors is an integer number (7225584).

Almost surely, 2^21676749 is an apocalyptic number.

It is an amenable number.

21676749 is a deficient number, since it is larger than the sum of its proper divisors (7225587).

21676749 is an equidigital number, since it uses as much as digits as its factorization.

21676749 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7225586.

The product of its digits is 127008, while the sum is 42.

The square root of 21676749 is about 4655.8295716231. The cubic root of 21676749 is about 278.8247894663.

The spelling of 21676749 in words is "twenty-one million, six hundred seventy-six thousand, seven hundred forty-nine".