21311352566 has 32 divisors (see below), whose sum is σ = 37987633152. Its totient is φ = 8774268480.

The previous prime is 21311352553. The next prime is 21311352577. The reversal of 21311352566 is 66525311312.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 119756 + ... + 238671.

It is an arithmetic number, because the mean of its divisors is an integer number (1187113536).

Almost surely, 2^21311352566 is an apocalyptic number.

21311352566 is a deficient number, since it is larger than the sum of its proper divisors (16676280586).

21311352566 is a wasteful number, since it uses less digits than its factorization.

21311352566 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 358604.

The product of its digits is 32400, while the sum is 35.

Adding to 21311352566 its reverse (66525311312), we get a palindrome (87836663878).

The spelling of 21311352566 in words is "twenty-one billion, three hundred eleven million, three hundred fifty-two thousand, five hundred sixty-six".