21381004 has 48 divisors (see below), whose sum is σ = 41580000. Its totient is φ = 9580032.

The previous prime is 21380981. The next prime is 21381037. The reversal of 21381004 is 40018312.

It is a Harshad number since it is a multiple of its sum of digits (19).

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 196102 + ... + 196210.

It is an arithmetic number, because the mean of its divisors is an integer number (866250).

Almost surely, 2^21381004 is an apocalyptic number.

It is an amenable number.

21381004 is a deficient number, since it is larger than the sum of its proper divisors (20198996).

21381004 is a wasteful number, since it uses less digits than its factorization.

21381004 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 250 (or 248 counting only the distinct ones).

The product of its (nonzero) digits is 192, while the sum is 19.

The square root of 21381004 is about 4623.9597749115. The cubic root of 21381004 is about 277.5509372718.

Adding to 21381004 its reverse (40018312), we get a palindrome (61399316).

The spelling of 21381004 in words is "twenty-one million, three hundred eighty-one thousand, four".