21250878 has 16 divisors (see below), whose sum is σ = 46365696. Its totient is φ = 6439640.

The previous prime is 21250877. The next prime is 21250961. The reversal of 21250878 is 87805212.

It is a Smith number, since the sum of its digits (33) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Harshad number since it is a multiple of its sum of digits (33).

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21250877) by changing a digit.

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 7 ways as a sum of consecutive naturals, for example, 160926 + ... + 161057.

It is an arithmetic number, because the mean of its divisors is an integer number (2897856).

Almost surely, 2^21250878 is an apocalyptic number.

21250878 is an abundant number, since it is smaller than the sum of its proper divisors (25114818).

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

21250878 is a wasteful number, since it uses less digits than its factorization.

21250878 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 321999.

The product of its (nonzero) digits is 8960, while the sum is 33.

The square root of 21250878 is about 4609.8674601338. The cubic root of 21250878 is about 276.9867275459.

The spelling of 21250878 in words is "twenty-one million, two hundred fifty thousand, eight hundred seventy-eight".