21506662765742 has 32 divisors (see below), whose sum is σ = 40220507335680. Its totient is φ = 8379166157280.

The previous prime is 21506662765661. The next prime is 21506662765789. The reversal of 21506662765742 is 24756726660512.

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, 31310168 + ... + 31989684.

It is an arithmetic number, because the mean of its divisors is an integer number (1256890854240).

Almost surely, 2^{21506662765742} is an apocalyptic number.

21506662765742 is a gapful number since it is divisible by the number (22) formed by its first and last digit.

21506662765742 is a deficient number, since it is larger than the sum of its proper divisors (18713844569938).

21506662765742 is a wasteful number, since it uses less digits than its factorization.

21506662765742 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 885056.

The product of its (nonzero) digits is 50803200, while the sum is 59.

The spelling of 21506662765742 in words is "twenty-one trillion, five hundred six billion, six hundred sixty-two million, seven hundred sixty-five thousand, seven hundred forty-two".