21101011643 has 16 divisors (see below), whose sum is σ = 22892173920. Its totient is φ = 19372179456.

The previous prime is 21101011619. The next prime is 21101011669. The reversal of 21101011643 is 34611010112.

It is a happy number.

It is not a de Polignac number, because 21101011643 - 2⁸ = 21101011387 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21101011543) 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, 543371 + ... + 580907.

It is an arithmetic number, because the mean of its divisors is an integer number (1430760870).

Almost surely, 2^21101011643 is an apocalyptic number.

21101011643 is a deficient number, since it is larger than the sum of its proper divisors (1791162277).

21101011643 is a wasteful number, since it uses less digits than its factorization.

21101011643 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 38366.

The product of its (nonzero) digits is 144, while the sum is 20.

Adding to 21101011643 its reverse (34611010112), we get a palindrome (55712021755).

The spelling of 21101011643 in words is "twenty-one billion, one hundred one million, eleven thousand, six hundred forty-three".