21425784 has 32 divisors (see below), whose sum is σ = 53831040. Its totient is φ = 7106400.

The previous prime is 21425783. The next prime is 21425801. The reversal of 21425784 is 48752412.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21425783) 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, 2949 + ... + 7179.

It is an arithmetic number, because the mean of its divisors is an integer number (1682220).

Almost surely, 2^21425784 is an apocalyptic number.

21425784 is a gapful number since it is divisible by the number (24) formed by its first and last digit.

It is an amenable number.

21425784 is an abundant number, since it is smaller than the sum of its proper divisors (32405256).

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

21425784 is a wasteful number, since it uses less digits than its factorization.

21425784 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4451 (or 4447 counting only the distinct ones).

The product of its digits is 17920, while the sum is 33.

The square root of 21425784 is about 4628.7994123747. The cubic root of 21425784 is about 277.7445680950.

The spelling of 21425784 in words is "twenty-one million, four hundred twenty-five thousand, seven hundred eighty-four".