21356254603646 has 16 divisors (see below), whose sum is σ = 32572896659520. Its totient is φ = 10498766050080.

The previous prime is 21356254603609. The next prime is 21356254603687. The reversal of 21356254603646 is 64630645265312.

It is a super-2 number, since 2×21356254603646² (a number of 27 digits) contains 22 as substring.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 35618006 + ... + 36212633.

It is an arithmetic number, because the mean of its divisors is an integer number (2035806041220).

Almost surely, 2^{21356254603646} is an apocalyptic number.

21356254603646 is a deficient number, since it is larger than the sum of its proper divisors (11216642055874).

21356254603646 is a wasteful number, since it uses less digits than its factorization.

21356254603646 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 71833139.

The product of its (nonzero) digits is 18662400, while the sum is 53.

Adding to 21356254603646 its reverse (64630645265312), we get a palindrome (85986899868958).

The spelling of 21356254603646 in words is "twenty-one trillion, three hundred fifty-six billion, two hundred fifty-four million, six hundred three thousand, six hundred forty-six".