21391733757 has 8 divisors (see below), whose sum is σ = 28667095776. Its totient is φ = 14188763792.

The previous prime is 21391733749. The next prime is 21391733773. The reversal of 21391733757 is 75733719312.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21391733757 - 2³ = 21391733749 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21391733707) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 18097323 + ... + 18098504.

It is an arithmetic number, because the mean of its divisors is an integer number (3583386972).

Almost surely, 2^21391733757 is an apocalyptic number.

It is an amenable number.

21391733757 is a deficient number, since it is larger than the sum of its proper divisors (7275362019).

21391733757 is a wasteful number, since it uses less digits than its factorization.

21391733757 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 36196027.

The product of its digits is 833490, while the sum is 48.

The spelling of 21391733757 in words is "twenty-one billion, three hundred ninety-one million, seven hundred thirty-three thousand, seven hundred fifty-seven".