21001004 has 24 divisors (see below), whose sum is σ = 38987760. Its totient is φ = 9870336.

The previous prime is 21000983. The next prime is 21001021. The reversal of 21001004 is 40010012.

It is a junction number, because it is equal to n+sod(n) for n = 21000982 and 21001000.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 9404 + ... + 11420.

It is an arithmetic number, because the mean of its divisors is an integer number (1624490).

Almost surely, 2^21001004 is an apocalyptic number.

It is an amenable number.

21001004 is a deficient number, since it is larger than the sum of its proper divisors (17986756).

21001004 is a wasteful number, since it uses less digits than its factorization.

21001004 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2177 (or 2175 counting only the distinct ones).

The product of its (nonzero) digits is 8, while the sum is 8.

The square root of 21001004 is about 4582.6852390274. The cubic root of 21001004 is about 275.8968143297.

Adding to 21001004 its reverse (40010012), we get a palindrome (61011016).

The spelling of 21001004 in words is "twenty-one million, one thousand, four".