21010101012121 has 8 divisors (see below), whose sum is σ = 22626321697224. Its totient is φ = 19393888765440.

The previous prime is 21010101012037. The next prime is 21010101012139. The reversal of 21010101012121 is 12121010101012.

It is a happy number.

21010101012121 is an esthetic number in base 10, because in such base its adjacent digits differ by 1.

It can be written as a sum of positive squares in 4 ways, for example, as 5000411545600 + 16009689466521 = 2236160^2 + 4001211^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21010101012121 - 2²⁵ = 21010067457689 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (13).

It is an alternating number because its digits alternate between even and odd.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21010101012421) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 3642441 + ... + 7435561.

It is an arithmetic number, because the mean of its divisors is an integer number (2828290212153).

Almost surely, 2^{21010101012121} is an apocalyptic number.

It is an amenable number.

21010101012121 is a deficient number, since it is larger than the sum of its proper divisors (1616220685103).

21010101012121 is a wasteful number, since it uses less digits than its factorization.

21010101012121 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4219211.

The product of its (nonzero) digits is 8, while the sum is 13.

Adding to 21010101012121 its reverse (12121010101012), we get a palindrome (33131111113133).

It can be divided in two parts, 21010101012 and 121, that multiplied together give a palindrome (2542222222452).

The spelling of 21010101012121 in words is "twenty-one trillion, ten billion, one hundred one million, twelve thousand, one hundred twenty-one".