21018313641 has 16 divisors (see below), whose sum is σ = 30311946560. Its totient is φ = 12877859520.

The previous prime is 21018313639. The next prime is 21018313649. The reversal of 21018313641 is 14631381012.

It is not a de Polignac number, because 21018313641 - 2¹ = 21018313639 is a prime.

It is a super-2 number, since 2×21018313641² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21018313599 and 21018313608.

It is not an unprimeable number, because it can be changed into a prime (21018313649) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1167775 + ... + 1185636.

It is an arithmetic number, because the mean of its divisors is an integer number (1894496660).

Almost surely, 2^21018313641 is an apocalyptic number.

It is an amenable number.

21018313641 is a deficient number, since it is larger than the sum of its proper divisors (9293632919).

21018313641 is a wasteful number, since it uses less digits than its factorization.

21018313641 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2353656.

The product of its (nonzero) digits is 3456, while the sum is 30.

Adding to 21018313641 its reverse (14631381012), we get a palindrome (35649694653).

The spelling of 21018313641 in words is "twenty-one billion, eighteen million, three hundred thirteen thousand, six hundred forty-one".