21442878 has 24 divisors (see below), whose sum is σ = 46548216. Its totient is φ = 7134000.

The previous prime is 21442871. The next prime is 21442913. The reversal of 21442878 is 87824412.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21442871) 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, 14053 + ... + 15503.

It is an arithmetic number, because the mean of its divisors is an integer number (1939509).

Almost surely, 2^21442878 is an apocalyptic number.

21442878 is an abundant number, since it is smaller than the sum of its proper divisors (25105338).

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

21442878 is a wasteful number, since it uses less digits than its factorization.

21442878 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2280 (or 2277 counting only the distinct ones).

The product of its digits is 28672, while the sum is 36.

The square root of 21442878 is about 4630.6455273536. The cubic root of 21442878 is about 277.8184122007.

The spelling of 21442878 in words is "twenty-one million, four hundred forty-two thousand, eight hundred seventy-eight".