21015551342242 has 4 divisors (see below), whose sum is σ = 31523327013366. Its totient is φ = 10507775671120.

The previous prime is 21015551342189. The next prime is 21015551342251. The reversal of 21015551342242 is 24224315551012.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in only one way, i.e., 18510482269161 + 2505069073081 = 4302381^2 + 1582741^2 .

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5253887835559 + ... + 5253887835562.

Almost surely, 2^{21015551342242} is an apocalyptic number.

21015551342242 is a deficient number, since it is larger than the sum of its proper divisors (10507775671124).

21015551342242 is a wasteful number, since it uses less digits than its factorization.

21015551342242 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10507775671123.

The product of its (nonzero) digits is 96000, while the sum is 37.

Adding to 21015551342242 its reverse (24224315551012), we get a palindrome (45239866893254).

The spelling of 21015551342242 in words is "twenty-one trillion, fifteen billion, five hundred fifty-one million, three hundred forty-two thousand, two hundred forty-two".