21772747 has 4 divisors (see below), whose sum is σ = 21843976. Its totient is φ = 21701520.

The previous prime is 21772741. The next prime is 21772759. The reversal of 21772747 is 74727712.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21772747 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21772741) 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 3 ways as a sum of consecutive naturals, for example, 35154 + ... + 35767.

It is an arithmetic number, because the mean of its divisors is an integer number (5460994).

Almost surely, 2^21772747 is an apocalyptic number.

21772747 is a deficient number, since it is larger than the sum of its proper divisors (71229).

21772747 is an equidigital number, since it uses as much as digits as its factorization.

21772747 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 71228.

The product of its digits is 38416, while the sum is 37.

The square root of 21772747 is about 4666.1276236297. The cubic root of 21772747 is about 279.2357859990.

The spelling of 21772747 in words is "twenty-one million, seven hundred seventy-two thousand, seven hundred forty-seven".