21621004 has 6 divisors (see below), whose sum is σ = 37836764. Its totient is φ = 10810500.

The previous prime is 21621001. The next prime is 21621007. The reversal of 21621004 is 40012612.

It is an interprime number because it is at equal distance from previous prime (21621001) and next prime (21621007).

It is not an unprimeable number, because it can be changed into a prime (21621001) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 2702622 + ... + 2702629.

Almost surely, 2^21621004 is an apocalyptic number.

It is an amenable number.

21621004 is a deficient number, since it is larger than the sum of its proper divisors (16215760).

21621004 is a wasteful number, since it uses less digits than its factorization.

21621004 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5405255 (or 5405253 counting only the distinct ones).

The product of its (nonzero) digits is 96, while the sum is 16.

The square root of 21621004 is about 4649.8391370025. The cubic root of 21621004 is about 278.5855710800.

Adding to 21621004 its reverse (40012612), we get a palindrome (61633616).

The spelling of 21621004 in words is "twenty-one million, six hundred twenty-one thousand, four".