21397739706 has 96 divisors (see below), whose sum is σ = 55700631168. Its totient is φ = 6029821440.

The previous prime is 21397739689. The next prime is 21397739711. The reversal of 21397739706 is 60793779312.

It is a happy number.

It is a Harshad number since it is a multiple of its sum of digits (54).

It is an unprimeable number.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 205266 + ... + 291426.

It is an arithmetic number, because the mean of its divisors is an integer number (580214908).

Almost surely, 2^21397739706 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21397739706, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (27850315584).

21397739706 is an abundant number, since it is smaller than the sum of its proper divisors (34302891462).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21397739706 is an equidigital number, since it uses as much as digits as its factorization.

21397739706 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 86258 (or 86246 counting only the distinct ones).

The product of its (nonzero) digits is 3000564, while the sum is 54.

The spelling of 21397739706 in words is "twenty-one billion, three hundred ninety-seven million, seven hundred thirty-nine thousand, seven hundred six".