21112001021 has 16 divisors (see below), whose sum is σ = 23097784320. Its totient is φ = 19210141440.

The previous prime is 21112000967. The next prime is 21112001033. The reversal of 21112001021 is 12010021112.

It is not a de Polignac number, because 21112001021 - 2¹⁸ = 21111738877 is a prime.

It is a super-4 number, since 4×21112001021⁴ (a number of 42 digits) contains 4444 as substring. Note that it is a super-d number also for d = 2.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21112000993 and 21112001011.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21112001041) 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, 528275 + ... + 566831.

It is an arithmetic number, because the mean of its divisors is an integer number (1443611520).

Almost surely, 2^21112001021 is an apocalyptic number.

It is an amenable number.

21112001021 is a deficient number, since it is larger than the sum of its proper divisors (1985783299).

21112001021 is a wasteful number, since it uses less digits than its factorization.

21112001021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 39644.

The product of its (nonzero) digits is 8, while the sum is 11.

Adding to 21112001021 its reverse (12010021112), we get a palindrome (33122022133).

The spelling of 21112001021 in words is "twenty-one billion, one hundred twelve million, one thousand, twenty-one".