21640641735 has 32 divisors (see below), whose sum is σ = 35308986048. Its totient is φ = 11314068480.

The previous prime is 21640641719. The next prime is 21640641739. The reversal of 21640641735 is 53714604612.

It is a happy number.

It is not a de Polignac number, because 21640641735 - 2⁴ = 21640641719 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21640641693 and 21640641702.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21640641739) 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 31 ways as a sum of consecutive naturals, for example, 953115 + ... + 975555.

It is an arithmetic number, because the mean of its divisors is an integer number (1103405814).

Almost surely, 2^21640641735 is an apocalyptic number.

21640641735 is a deficient number, since it is larger than the sum of its proper divisors (13668344313).

21640641735 is a wasteful number, since it uses less digits than its factorization.

21640641735 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 23715.

The product of its (nonzero) digits is 120960, while the sum is 39.

The spelling of 21640641735 in words is "twenty-one billion, six hundred forty million, six hundred forty-one thousand, seven hundred thirty-five".