21425400 has 72 divisors (see below), whose sum is σ = 71959680. Its totient is φ = 5712960.

The previous prime is 21425399. The next prime is 21425401. The reversal of 21425400 is 452412.

It is an interprime number because it is at equal distance from previous prime (21425399) and next prime (21425401).

It is a tau number, because it is divible by the number of its divisors (72).

It is a Harshad number since it is a multiple of its sum of digits (18).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21425401) by changing a digit.

It is a polite number, since it can be written in 17 ways as a sum of consecutive naturals, for example, 4152 + ... + 7751.

It is an arithmetic number, because the mean of its divisors is an integer number (999440).

Almost surely, 2^21425400 is an apocalyptic number.

21425400 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21425400 is an abundant number, since it is smaller than the sum of its proper divisors (50534280).

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

21425400 is a wasteful number, since it uses less digits than its factorization.

21425400 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 11925 (or 11913 counting only the distinct ones).

The product of its (nonzero) digits is 320, while the sum is 18.

The square root of 21425400 is about 4628.7579327504. The cubic root of 21425400 is about 277.7429088083.

Adding to 21425400 its reverse (452412), we get a palindrome (21877812).

The spelling of 21425400 in words is "twenty-one million, four hundred twenty-five thousand, four hundred".