21678221907 has 24 divisors (see below), whose sum is σ = 31963097088. Its totient is φ = 14154134400.

The previous prime is 21678221867. The next prime is 21678221927. The reversal of 21678221907 is 70912287612.

It is a happy number.

It is not a de Polignac number, because 21678221907 - 2¹⁵ = 21678189139 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21678221927) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 43182 + ... + 212652.

It is an arithmetic number, because the mean of its divisors is an integer number (1331795712).

Almost surely, 2^21678221907 is an apocalyptic number.

21678221907 is a deficient number, since it is larger than the sum of its proper divisors (10284875181).

21678221907 is a wasteful number, since it uses less digits than its factorization.

21678221907 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 169771 (or 169768 counting only the distinct ones).

The product of its (nonzero) digits is 169344, while the sum is 45.

It can be divided in two parts, 2167822 and 1907, that added together give a square (2169729 = 1473²).

The spelling of 21678221907 in words is "twenty-one billion, six hundred seventy-eight million, two hundred twenty-one thousand, nine hundred seven".