21391733707 has 2 divisors, whose sum is σ = 21391733708. Its totient is φ = 21391733706.

The previous prime is 21391733677. The next prime is 21391733731. The reversal of 21391733707 is 70733719312.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21391733707 - 2³¹ = 19244250059 is a prime.

It is not a weakly prime, because it can be changed into another prime (21391733747) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10695866853 + 10695866854.

It is an arithmetic number, because the mean of its divisors is an integer number (10695866854).

Almost surely, 2^21391733707 is an apocalyptic number.

21391733707 is a deficient number, since it is larger than the sum of its proper divisors (1).

21391733707 is an equidigital number, since it uses as much as digits as its factorization.

21391733707 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 166698, while the sum is 43.

The spelling of 21391733707 in words is "twenty-one billion, three hundred ninety-one million, seven hundred thirty-three thousand, seven hundred seven".