21001124 has 6 divisors (see below), whose sum is σ = 36751974. Its totient is φ = 10500560.

The previous prime is 21001121. The next prime is 21001153. The reversal of 21001124 is 42110012.

It can be written as a sum of positive squares in only one way, i.e., 20994724 + 6400 = 4582^2 + 80^2 .

It is not an unprimeable number, because it can be changed into a prime (21001121) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 2625137 + ... + 2625144.

It is an arithmetic number, because the mean of its divisors is an integer number (6125329).

Almost surely, 2^21001124 is an apocalyptic number.

It is an amenable number.

21001124 is a deficient number, since it is larger than the sum of its proper divisors (15750850).

21001124 is a wasteful number, since it uses less digits than its factorization.

21001124 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5250285 (or 5250283 counting only the distinct ones).

The product of its (nonzero) digits is 16, while the sum is 11.

The square root of 21001124 is about 4582.6983317692. The cubic root of 21001124 is about 275.8973398214.

Adding to 21001124 its reverse (42110012), we get a palindrome (63111136).

The spelling of 21001124 in words is "twenty-one million, one thousand, one hundred twenty-four".