21131012021 has 16 divisors (see below), whose sum is σ = 24890150784. Its totient is φ = 17560442304.

The previous prime is 21131012009. The next prime is 21131012029. The reversal of 21131012021 is 12021013112.

It is a cyclic number.

It is not a de Polignac number, because 21131012021 - 2³⁰ = 20057270197 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21131011987 and 21131012005.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21131012029) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 70850 + ... + 217443.

It is an arithmetic number, because the mean of its divisors is an integer number (1555634424).

Almost surely, 2^21131012021 is an apocalyptic number.

It is an amenable number.

21131012021 is a deficient number, since it is larger than the sum of its proper divisors (3759138763).

21131012021 is a wasteful number, since it uses less digits than its factorization.

21131012021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 288620.

The product of its (nonzero) digits is 24, while the sum is 14.

Adding to 21131012021 its reverse (12021013112), we get a palindrome (33152025133).

The spelling of 21131012021 in words is "twenty-one billion, one hundred thirty-one million, twelve thousand, twenty-one".