21010121 has 8 divisors (see below), whose sum is σ = 23148288. Its totient is φ = 18910000.

The previous prime is 21010111. The next prime is 21010127. The reversal of 21010121 is 12101012.

21010121 is an esthetic number in base 10, because in such base its adjacent digits differ by 1.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21010121 is a prime.

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

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21010099 and 21010108.

It is not an unprimeable number, because it can be changed into a prime (21010127) 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, 8345 + ... + 10566.

It is an arithmetic number, because the mean of its divisors is an integer number (2893536).

Almost surely, 2^21010121 is an apocalyptic number.

It is an amenable number.

21010121 is a deficient number, since it is larger than the sum of its proper divisors (2138167).

21010121 is a wasteful number, since it uses less digits than its factorization.

21010121 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 19023.

The product of its (nonzero) digits is 4, while the sum is 8.

The square root of 21010121 is about 4583.6798535674. The cubic root of 21010121 is about 275.9367328555.

Adding to 21010121 its reverse (12101012), we get a palindrome (33111133).

The spelling of 21010121 in words is "twenty-one million, ten thousand, one hundred twenty-one".