210121210220021 has 8 divisors (see below), whose sum is σ = 223025245430040. Its totient is φ = 197277615456768.

The previous prime is 210121210220003. The next prime is 210121210220029. The reversal of 210121210220021 is 120022012121012.

It can be written as a sum of positive squares in 4 ways, for example, as 136434197055025 + 73687013164996 = 11680505^2 + 8584114^2 .

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

It is a de Polignac number, because none of the positive numbers 2^k-210121210220021 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (17).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (210121210220029) 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, 15110104526 + ... + 15110118431.

It is an arithmetic number, because the mean of its divisors is an integer number (27878155678755).

Almost surely, 2^{210121210220021} is an apocalyptic number.

It is an amenable number.

210121210220021 is a deficient number, since it is larger than the sum of its proper divisors (12904035210019).

210121210220021 is a wasteful number, since it uses less digits than its factorization.

210121210220021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 30220223383.

The product of its (nonzero) digits is 64, while the sum is 17.

Adding to 210121210220021 its reverse (120022012121012), we get a palindrome (330143222341033).

The spelling of 210121210220021 in words is "two hundred ten trillion, one hundred twenty-one billion, two hundred ten million, two hundred twenty thousand, twenty-one".