21214205351661 has 16 divisors (see below), whose sum is σ = 32398404624000. Its totient is φ = 12095404382208.

The previous prime is 21214205351657. The next prime is 21214205351723. The reversal of 21214205351661 is 16615350241212.

It is not a de Polignac number, because 21214205351661 - 2² = 21214205351657 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21214204351661) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1124935176 + ... + 1124954033.

It is an arithmetic number, because the mean of its divisors is an integer number (2024900289000).

Almost surely, 2^{21214205351661} is an apocalyptic number.

21214205351661 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

It is an amenable number.

21214205351661 is a deficient number, since it is larger than the sum of its proper divisors (11184199272339).

21214205351661 is a wasteful number, since it uses less digits than its factorization.

21214205351661 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2249889668.

The product of its (nonzero) digits is 86400, while the sum is 39.

Adding to 21214205351661 its reverse (16615350241212), we get a palindrome (37829555592873).

The spelling of 21214205351661 in words is "twenty-one trillion, two hundred fourteen billion, two hundred five million, three hundred fifty-one thousand, six hundred sixty-one".