21912438 has 16 divisors (see below), whose sum is σ = 43969536. Its totient is φ = 7280040.

The previous prime is 21912431. The next prime is 21912461. The reversal of 21912438 is 83421912.

It is a Curzon number.

It is a plaindrome in base 8.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21912431) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 4006 + ... + 7737.

It is an arithmetic number, because the mean of its divisors is an integer number (2748096).

Almost surely, 2^21912438 is an apocalyptic number.

21912438 is an abundant number, since it is smaller than the sum of its proper divisors (22057098).

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

21912438 is a wasteful number, since it uses less digits than its factorization.

21912438 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 12059.

The product of its digits is 3456, while the sum is 30.

The square root of 21912438 is about 4681.0723130496. The cubic root of 21912438 is about 279.8316930693.

The spelling of 21912438 in words is "twenty-one million, nine hundred twelve thousand, four hundred thirty-eight".