21001000001121 has 24 divisors (see below), whose sum is σ = 34748382905600. Its totient is φ = 11972856468096.

The previous prime is 21001000001101. The next prime is 21001000001141. The reversal of 21001000001121 is 12110000010012.

It is a happy number.

It is an interprime number because it is at equal distance from previous prime (21001000001101) and next prime (21001000001141).

It is not a de Polignac number, because 21001000001121 - 2⁶ = 21001000001057 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (9).

It is not an unprimeable number, because it can be changed into a prime (21001000001101) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 384902521 + ... + 384957078.

Almost surely, 2^{21001000001121} is an apocalyptic number.

21001000001121 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

It is an amenable number.

21001000001121 is a deficient number, since it is larger than the sum of its proper divisors (13747382904479).

21001000001121 is a wasteful number, since it uses less digits than its factorization.

21001000001121 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 769860045 (or 769860042 counting only the distinct ones).

The product of its (nonzero) digits is 4, while the sum is 9.

Adding to 21001000001121 its reverse (12110000010012), we get a palindrome (33111000011133).

The spelling of 21001000001121 in words is "twenty-one trillion, one billion, one thousand, one hundred twenty-one".