21405426 has 16 divisors (see below), whose sum is σ = 48926784. Its totient is φ = 6115824.

The previous prime is 21405409. The next prime is 21405427. The reversal of 21405426 is 62450412.

It is a junction number, because it is equal to n+sod(n) for n = 21405396 and 21405405.

It is not an unprimeable number, because it can be changed into a prime (21405427) 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, 254785 + ... + 254868.

It is an arithmetic number, because the mean of its divisors is an integer number (3057924).

Almost surely, 2^21405426 is an apocalyptic number.

21405426 is an abundant number, since it is smaller than the sum of its proper divisors (27521358).

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

21405426 is a wasteful number, since it uses less digits than its factorization.

21405426 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 509665.

The product of its (nonzero) digits is 1920, while the sum is 24.

The square root of 21405426 is about 4626.5998314097. The cubic root of 21405426 is about 277.6565726264.

Adding to 21405426 its reverse (62450412), we get a palindrome (83855838).

The spelling of 21405426 in words is "twenty-one million, four hundred five thousand, four hundred twenty-six".