21012022121 has 4 divisors (see below), whose sum is σ = 21012716244. Its totient is φ = 21011328000.

The previous prime is 21012022103. The next prime is 21012022139. The reversal of 21012022121 is 12122021012.

It is a semiprime because it is the product of two primes.

It is an interprime number because it is at equal distance from previous prime (21012022103) and next prime (21012022139).

It can be written as a sum of positive squares in 2 ways, for example, as 149108521 + 20862913600 = 12211^2 + 144440^2 .

It is a cyclic number.

It is not a de Polignac number, because 21012022121 - 2¹⁴ = 21012005737 is a prime.

It is a super-2 number, since 2×21012022121² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21012022096 and 21012022105.

It is not an unprimeable number, because it can be changed into a prime (21012072121) 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, 299480 + ... + 362921.

It is an arithmetic number, because the mean of its divisors is an integer number (5253179061).

Almost surely, 2^21012022121 is an apocalyptic number.

It is an amenable number.

21012022121 is a deficient number, since it is larger than the sum of its proper divisors (694123).

21012022121 is an equidigital number, since it uses as much as digits as its factorization.

21012022121 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 694122.

The product of its (nonzero) digits is 32, while the sum is 14.

Adding to 21012022121 its reverse (12122021012), we get a palindrome (33134043133).

The spelling of 21012022121 in words is "twenty-one billion, twelve million, twenty-two thousand, one hundred twenty-one".