21772679 has 4 divisors (see below), whose sum is σ = 21806280. Its totient is φ = 21739080.

The previous prime is 21772607. The next prime is 21772691. The reversal of 21772679 is 97627712.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 21772679 - 2¹² = 21768583 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21772379) 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, 15809 + ... + 17130.

It is an arithmetic number, because the mean of its divisors is an integer number (5451570).

Almost surely, 2^21772679 is an apocalyptic number.

21772679 is a deficient number, since it is larger than the sum of its proper divisors (33601).

21772679 is an equidigital number, since it uses as much as digits as its factorization.

21772679 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 33600.

The product of its digits is 74088, while the sum is 41.

The square root of 21772679 is about 4666.1203370680. The cubic root of 21772679 is about 279.2354952984.

The spelling of 21772679 in words is "twenty-one million, seven hundred seventy-two thousand, six hundred seventy-nine".