21782649 has 16 divisors (see below), whose sum is σ = 33259520. Its totient is φ = 12422160.

The previous prime is 21782647. The next prime is 21782653. The reversal of 21782649 is 94628712.

It is not a de Polignac number, because 21782649 - 2¹ = 21782647 is a prime.

It is a Smith number, since the sum of its digits (39) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is not an unprimeable number, because it can be changed into a prime (21782647) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 16392 + ... + 17670.

It is an arithmetic number, because the mean of its divisors is an integer number (2078720).

Almost surely, 2^21782649 is an apocalyptic number.

It is an amenable number.

21782649 is a deficient number, since it is larger than the sum of its proper divisors (11476871).

21782649 is a wasteful number, since it uses less digits than its factorization.

21782649 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2100.

The product of its digits is 48384, while the sum is 39.

The square root of 21782649 is about 4667.1885541512. The cubic root of 21782649 is about 279.2781106797.

The spelling of 21782649 in words is "twenty-one million, seven hundred eighty-two thousand, six hundred forty-nine".