21512010021 has 16 divisors (see below), whose sum is σ = 29678036160. Its totient is φ = 13843872000.

The previous prime is 21512010019. The next prime is 21512010041. The reversal of 21512010021 is 12001021512.

It is not a de Polignac number, because 21512010021 - 2¹ = 21512010019 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21512010041) 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, 431646 + ... + 478896.

It is an arithmetic number, because the mean of its divisors is an integer number (1854877260).

Almost surely, 2^21512010021 is an apocalyptic number.

It is an amenable number.

21512010021 is a deficient number, since it is larger than the sum of its proper divisors (8166026139).

21512010021 is a wasteful number, since it uses less digits than its factorization.

21512010021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 52516.

The product of its (nonzero) digits is 40, while the sum is 15.

Adding to 21512010021 its reverse (12001021512), we get a palindrome (33513031533).

The spelling of 21512010021 in words is "twenty-one billion, five hundred twelve million, ten thousand, twenty-one".