21122478 has 32 divisors (see below), whose sum is σ = 50551200. Its totient is φ = 6499008.

The previous prime is 21122473. The next prime is 21122561. The reversal of 21122478 is 87422112.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21122473) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 14343 + ... + 15746.

It is an arithmetic number, because the mean of its divisors is an integer number (1579725).

Almost surely, 2^21122478 is an apocalyptic number.

21122478 is an abundant number, since it is smaller than the sum of its proper divisors (29428722).

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

21122478 is a wasteful number, since it uses less digits than its factorization.

21122478 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 30113 (or 30107 counting only the distinct ones).

The product of its digits is 1792, while the sum is 27.

The square root of 21122478 is about 4595.9197120925. The cubic root of 21122478 is about 276.4277394019.

The spelling of 21122478 in words is "twenty-one million, one hundred twenty-two thousand, four hundred seventy-eight".