21967647 has 16 divisors (see below), whose sum is σ = 32081280. Its totient is φ = 13288032.

The previous prime is 21967637. The next prime is 21967651. The reversal of 21967647 is 74676912.

It is not a de Polignac number, because 21967647 - 2¹¹ = 21965599 is a prime.

It is a plaindrome in base 11.

It is a junction number, because it is equal to n+sod(n) for n = 21967599 and 21967608.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21967637) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 2473 + ... + 7074.

It is an arithmetic number, because the mean of its divisors is an integer number (2005080).

Almost surely, 2^21967647 is an apocalyptic number.

21967647 is a deficient number, since it is larger than the sum of its proper divisors (10113633).

21967647 is a wasteful number, since it uses less digits than its factorization.

21967647 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9622.

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

The square root of 21967647 is about 4686.9656495434. The cubic root of 21967647 is about 280.0665105605.

The spelling of 21967647 in words is "twenty-one million, nine hundred sixty-seven thousand, six hundred forty-seven".