21100402 has 4 divisors (see below), whose sum is σ = 31650606. Its totient is φ = 10550200.

The previous prime is 21100399. The next prime is 21100403. The reversal of 21100402 is 20400112.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in only one way, i.e., 13097161 + 8003241 = 3619^2 + 2829^2 .

It is not an unprimeable number, because it can be changed into a prime (21100403) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5275099 + ... + 5275102.

Almost surely, 2^21100402 is an apocalyptic number.

21100402 is a deficient number, since it is larger than the sum of its proper divisors (10550204).

21100402 is a wasteful number, since it uses less digits than its factorization.

21100402 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10550203.

The product of its (nonzero) digits is 16, while the sum is 10.

The square root of 21100402 is about 4593.5173886685. The cubic root of 21100402 is about 276.3314037040.

Adding to 21100402 its reverse (20400112), we get a palindrome (41500514).

The spelling of 21100402 in words is "twenty-one million, one hundred thousand, four hundred two".