21742743619678 has 4 divisors (see below), whose sum is σ = 32614115429520. Its totient is φ = 10871371809838.

The previous prime is 21742743619643. The next prime is 21742743619697. The reversal of 21742743619678 is 87691634724712.

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

It is a super-2 number, since 2×21742743619678² (a number of 27 digits) contains 22 as substring.

It is a Smith number, since the sum of its digits (67) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5435685904918 + ... + 5435685904921.

It is an arithmetic number, because the mean of its divisors is an integer number (8153528857380).

Almost surely, 2^{21742743619678} is an apocalyptic number.

21742743619678 is a deficient number, since it is larger than the sum of its proper divisors (10871371809842).

21742743619678 is a wasteful number, since it uses less digits than its factorization.

21742743619678 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10871371809841.

The product of its digits is 170698752, while the sum is 67.

The spelling of 21742743619678 in words is "twenty-one trillion, seven hundred forty-two billion, seven hundred forty-three million, six hundred nineteen thousand, six hundred seventy-eight".