21425418 has 32 divisors (see below), whose sum is σ = 54414720. Its totient is φ = 6121440.

The previous prime is 21425413. The next prime is 21425419. The reversal of 21425418 is 81452412.

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

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 21425391 and 21425400.

It is not an unprimeable number, because it can be changed into a prime (21425413) 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, 27963 + ... + 28718.

It is an arithmetic number, because the mean of its divisors is an integer number (1700460).

Almost surely, 2^21425418 is an apocalyptic number.

21425418 is an abundant number, since it is smaller than the sum of its proper divisors (32989302).

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

21425418 is a wasteful number, since it uses less digits than its factorization.

21425418 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 56699 (or 56693 counting only the distinct ones).

The product of its digits is 2560, while the sum is 27.

The square root of 21425418 is about 4628.7598771161. The cubic root of 21425418 is about 277.7429865878.

The spelling of 21425418 in words is "twenty-one million, four hundred twenty-five thousand, four hundred eighteen".