21221210201021 has 16 divisors (see below), whose sum is σ = 22748419249776. Its totient is φ = 19726470414336.

The previous prime is 21221210201017. The next prime is 21221210201117. The reversal of 21221210201021 is 12010201212212.

It can be written as a sum of positive squares in 8 ways, for example, as 6799520392921 + 14421689808100 = 2607589^2 + 3797590^2 .

It is not a de Polignac number, because 21221210201021 - 2² = 21221210201017 is a prime.

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

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21221210261021) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 22667396 + ... + 23585021.

It is an arithmetic number, because the mean of its divisors is an integer number (1421776203111).

Almost surely, 2^{21221210201021} is an apocalyptic number.

It is an amenable number.

21221210201021 is a deficient number, since it is larger than the sum of its proper divisors (1527209048755).

21221210201021 is a wasteful number, since it uses less digits than its factorization.

21221210201021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 46252768.

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

Adding to 21221210201021 its reverse (12010201212212), we get a palindrome (33231411413233).

The spelling of 21221210201021 in words is "twenty-one trillion, two hundred twenty-one billion, two hundred ten million, two hundred one thousand, twenty-one".