21056310684 has 72 divisors (see below), whose sum is σ = 53594835840. Its totient is φ = 6970260000.

The previous prime is 21056310677. The next prime is 21056310689. The reversal of 21056310684 is 48601365012.

It is a happy number.

21056310684 is a `hidden beast` number, since 2 + 1 + 0 + 563 + 10 + 6 + 84 = 666.

It is a super-2 number, since 2×21056310684² (a number of 21 digits) contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21056310689) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 3240679 + ... + 3247169.

It is an arithmetic number, because the mean of its divisors is an integer number (744372720).

Almost surely, 2^21056310684 is an apocalyptic number.

It is an amenable number.

21056310684 is an abundant number, since it is smaller than the sum of its proper divisors (32538525156).

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

21056310684 is a wasteful number, since it uses less digits than its factorization.

21056310684 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7111 (or 7106 counting only the distinct ones).

The product of its (nonzero) digits is 34560, while the sum is 36.

Adding to 21056310684 its reverse (48601365012), we get a palindrome (69657675696).

The spelling of 21056310684 in words is "twenty-one billion, fifty-six million, three hundred ten thousand, six hundred eighty-four".