21939385 has 8 divisors (see below), whose sum is σ = 28352520. Its totient is φ = 16201344.

The previous prime is 21939383. The next prime is 21939391. The reversal of 21939385 is 58393912.

It can be written as a sum of positive squares in 4 ways, for example, as 558009 + 21381376 = 747^2 + 4624^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21939385 - 2¹ = 21939383 is a prime.

It is a super-2 number, since 2×21939385² = 962673228356450, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (21939383) 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 7 ways as a sum of consecutive naturals, for example, 168700 + ... + 168829.

It is an arithmetic number, because the mean of its divisors is an integer number (3544065).

Almost surely, 2^21939385 is an apocalyptic number.

It is an amenable number.

21939385 is a deficient number, since it is larger than the sum of its proper divisors (6413135).

21939385 is a wasteful number, since it uses less digits than its factorization.

21939385 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 337547.

The product of its digits is 58320, while the sum is 40.

The square root of 21939385 is about 4683.9497221896. The cubic root of 21939385 is about 279.9463545186.

The spelling of 21939385 in words is "twenty-one million, nine hundred thirty-nine thousand, three hundred eighty-five".