21531426 has 32 divisors (see below), whose sum is σ = 49354368. Its totient is φ = 6134400.

The previous prime is 21531379. The next prime is 21531439. The reversal of 21531426 is 62413512.

It is a junction number, because it is equal to n+sod(n) for n = 21531396 and 21531405.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 24816 + ... + 25668.

It is an arithmetic number, because the mean of its divisors is an integer number (1542324).

Almost surely, 2^21531426 is an apocalyptic number.

21531426 is an abundant number, since it is smaller than the sum of its proper divisors (27822942).

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

21531426 is a wasteful number, since it uses less digits than its factorization.

21531426 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1466.

The product of its digits is 1440, while the sum is 24.

The square root of 21531426 is about 4640.1967630694. The cubic root of 21531426 is about 278.2003024817.

Adding to 21531426 its reverse (62413512), we get a palindrome (83944938).

The spelling of 21531426 in words is "twenty-one million, five hundred thirty-one thousand, four hundred twenty-six".