21124124021 has 16 divisors (see below), whose sum is σ = 28362461568. Its totient is φ = 15194174400.

The previous prime is 21124124003. The next prime is 21124124029. The reversal of 21124124021 is 12042142112.

It is a cyclic number.

It is not a de Polignac number, because 21124124021 - 2⁶ = 21124123957 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21124123984 and 21124124002.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21124124029) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 10550510 + ... + 10552511.

It is an arithmetic number, because the mean of its divisors is an integer number (1772653848).

Almost surely, 2^21124124021 is an apocalyptic number.

It is an amenable number.

21124124021 is a deficient number, since it is larger than the sum of its proper divisors (7238337547).

21124124021 is a wasteful number, since it uses less digits than its factorization.

21124124021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 21103052.

The product of its (nonzero) digits is 256, while the sum is 20.

Adding to 21124124021 its reverse (12042142112), we get a palindrome (33166266133).

The spelling of 21124124021 in words is "twenty-one billion, one hundred twenty-four million, one hundred twenty-four thousand, twenty-one".