21353430 has 64 divisors (see below), whose sum is σ = 61129728. Its totient is φ = 4667520.

The previous prime is 21353419. The next prime is 21353441. The reversal of 21353430 is 3435312.

It is an interprime number because it is at equal distance from previous prime (21353419) and next prime (21353441).

It is a Harshad number since it is a multiple of its sum of digits (21).

It is a junction number, because it is equal to n+sod(n) for n = 21353397 and 21353406.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 2620 + ... + 7040.

It is an arithmetic number, because the mean of its divisors is an integer number (955152).

Almost surely, 2^21353430 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21353430, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (30564864).

21353430 is an abundant number, since it is smaller than the sum of its proper divisors (39776298).

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

21353430 is a wasteful number, since it uses less digits than its factorization.

21353430 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4461.

The product of its (nonzero) digits is 1080, while the sum is 21.

The square root of 21353430 is about 4620.9771693874. The cubic root of 21353430 is about 277.4315714727.

Adding to 21353430 its reverse (3435312), we get a palindrome (24788742).

It can be divided in two parts, 2135 and 3430, that added together give a triangular number (5565 = T₁₀₅).

The spelling of 21353430 in words is "twenty-one million, three hundred fifty-three thousand, four hundred thirty".