21381426 has 36 divisors (see below), whose sum is σ = 50925966. Its totient is φ = 6478560.

The previous prime is 21381407. The next prime is 21381433. The reversal of 21381426 is 62418312.

It can be written as a sum of positive squares in only one way, i.e., 11553201 + 9828225 = 3399^2 + 3135^2 .

It is a self number, because there is not a number n which added to its sum of digits gives 21381426.

It is an unprimeable number.

It is a polite number, since it can be written in 17 ways as a sum of consecutive naturals, for example, 2731 + ... + 7086.

Almost surely, 2^21381426 is an apocalyptic number.

21381426 is an abundant number, since it is smaller than the sum of its proper divisors (29544540).

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

21381426 is a wasteful number, since it uses less digits than its factorization.

21381426 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9847 (or 9833 counting only the distinct ones).

The product of its digits is 2304, while the sum is 27.

The square root of 21381426 is about 4624.0054065712. The cubic root of 21381426 is about 277.5527632809.

Adding to 21381426 its reverse (62418312), we get a palindrome (83799738).

The spelling of 21381426 in words is "twenty-one million, three hundred eighty-one thousand, four hundred twenty-six".