21669786 has 24 divisors (see below), whose sum is σ = 48571380. Its totient is φ = 6974016.

The previous prime is 21669763. The next prime is 21669787. The reversal of 21669786 is 68796612.

It can be written as a sum of positive squares in 2 ways, for example, as 21206025 + 463761 = 4605^2 + 681^2 .

It is not an unprimeable number, because it can be changed into a prime (21669787) 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 11 ways as a sum of consecutive naturals, for example, 20235 + ... + 21278.

Almost surely, 2^21669786 is an apocalyptic number.

21669786 is an abundant number, since it is smaller than the sum of its proper divisors (26901594).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21669786 is a wasteful number, since it uses less digits than its factorization.

21669786 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 41550 (or 41547 counting only the distinct ones).

The product of its digits is 217728, while the sum is 45.

The square root of 21669786 is about 4655.0817393468. The cubic root of 21669786 is about 278.7949315923.

The spelling of 21669786 in words is "twenty-one million, six hundred sixty-nine thousand, seven hundred eighty-six".