21004101 has 24 divisors (see below), whose sum is σ = 32248320. Its totient is φ = 13136256.

The previous prime is 21004099. The next prime is 21004117. The reversal of 21004101 is 10140012.

It is a happy number.

It is not a de Polignac number, because 21004101 - 2¹ = 21004099 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (9).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21004301) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 18780 + ... + 19866.

It is an arithmetic number, because the mean of its divisors is an integer number (1343680).

Almost surely, 2^21004101 is an apocalyptic number.

It is an amenable number.

21004101 is a deficient number, since it is larger than the sum of its proper divisors (11244219).

21004101 is a wasteful number, since it uses less digits than its factorization.

21004101 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1225 (or 1222 counting only the distinct ones).

The product of its (nonzero) digits is 8, while the sum is 9.

The square root of 21004101 is about 4583.0231288965. The cubic root of 21004101 is about 275.9103757518.

Adding to 21004101 its reverse (10140012), we get a palindrome (31144113).

The spelling of 21004101 in words is "twenty-one million, four thousand, one hundred one".