21263430 has 64 divisors (see below), whose sum is σ = 54571968. Its totient is φ = 5283840.

The previous prime is 21263399. The next prime is 21263443. The reversal of 21263430 is 3436212.

It is a happy number.

It is a junction number, because it is equal to n+sod(n) for n = 21263397 and 21263406.

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, 88110 + ... + 88350.

It is an arithmetic number, because the mean of its divisors is an integer number (852687).

Almost surely, 2^21263430 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21263430, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (27285984).

21263430 is an abundant number, since it is smaller than the sum of its proper divisors (33308538).

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

21263430 is a wasteful number, since it uses less digits than its factorization.

21263430 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 441.

The product of its (nonzero) digits is 864, while the sum is 21.

The square root of 21263430 is about 4611.2286865867. The cubic root of 21263430 is about 277.0412516164.

Adding to 21263430 its reverse (3436212), we get a palindrome (24699642).

The spelling of 21263430 in words is "twenty-one million, two hundred sixty-three thousand, four hundred thirty".