21939476 has 12 divisors (see below), whose sum is σ = 41347572. Its totient is φ = 10125888.

The previous prime is 21939461. The next prime is 21939481. The reversal of 21939476 is 67493912.

It can be written as a sum of positive squares in 2 ways, for example, as 12180100 + 9759376 = 3490^2 + 3124^2 .

It is a congruent number.

It is an unprimeable number.

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 3 ways as a sum of consecutive naturals, for example, 210905 + ... + 211008.

It is an arithmetic number, because the mean of its divisors is an integer number (3445631).

Almost surely, 2^21939476 is an apocalyptic number.

21939476 is a gapful number since it is divisible by the number (26) formed by its first and last digit.

It is an amenable number.

21939476 is a deficient number, since it is larger than the sum of its proper divisors (19408096).

21939476 is a wasteful number, since it uses less digits than its factorization.

21939476 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 421930 (or 421928 counting only the distinct ones).

The product of its digits is 81648, while the sum is 41.

The square root of 21939476 is about 4683.9594362035. The cubic root of 21939476 is about 279.9467415711.

The spelling of 21939476 in words is "twenty-one million, nine hundred thirty-nine thousand, four hundred seventy-six".