21391733758 has 4 divisors (see below), whose sum is σ = 32087600640. Its totient is φ = 10695866878.

The previous prime is 21391733749. The next prime is 21391733773. The reversal of 21391733758 is 85733719312.

It is a happy number.

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

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, 5347933438 + ... + 5347933441.

It is an arithmetic number, because the mean of its divisors is an integer number (8021900160).

Almost surely, 2^21391733758 is an apocalyptic number.

21391733758 is a deficient number, since it is larger than the sum of its proper divisors (10695866882).

21391733758 is a wasteful number, since it uses less digits than its factorization.

21391733758 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10695866881.

The product of its digits is 952560, while the sum is 49.

The spelling of 21391733758 in words is "twenty-one billion, three hundred ninety-one million, seven hundred thirty-three thousand, seven hundred fifty-eight".