21347136640 has 192 divisors, whose sum is σ = 55986451560. Its totient is φ = 7756120064.

The previous prime is 21347136541. The next prime is 21347136647. The reversal of 21347136640 is 4663174312.

It can be written as a sum of positive squares in 12 ways, for example, as 3448977984 + 17898158656 = 58728^2 + 133784^2 .

It is a hoax number, since the sum of its digits (37) coincides with the sum of the digits of its distinct prime factors.

It is a self number, because there is not a number n which added to its sum of digits gives 21347136640.

It is not an unprimeable number, because it can be changed into a prime (21347136647) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 9148914 + ... + 9151246.

Almost surely, 2^21347136640 is an apocalyptic number.

21347136640 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21347136640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (27993225780).

21347136640 is an abundant number, since it is smaller than the sum of its proper divisors (34639314920).

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

21347136640 is a wasteful number, since it uses less digits than its factorization.

21347136640 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2427 (or 2386 counting only the distinct ones).

The product of its (nonzero) digits is 72576, while the sum is 37.

The spelling of 21347136640 in words is "twenty-one billion, three hundred forty-seven million, one hundred thirty-six thousand, six hundred forty".