21020012128 has 24 divisors (see below), whose sum is σ = 42084561960. Its totient is φ = 10331869440.

The previous prime is 21020012099. The next prime is 21020012129. The reversal of 21020012128 is 82121002012.

It is a super-2 number, since 2×21020012128² (a number of 21 digits) contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21020012129) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 5564853 + ... + 5568628.

It is an arithmetic number, because the mean of its divisors is an integer number (1753523415).

Almost surely, 2^21020012128 is an apocalyptic number.

It is an amenable number.

21020012128 is an abundant number, since it is smaller than the sum of its proper divisors (21064549832).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21020012128 is a wasteful number, since it uses less digits than its factorization.

21020012128 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 11133550 (or 11133542 counting only the distinct ones).

The product of its (nonzero) digits is 128, while the sum is 19.

The spelling of 21020012128 in words is "twenty-one billion, twenty million, twelve thousand, one hundred twenty-eight".