21101013 has 8 divisors (see below), whose sum is σ = 31260800. Its totient is φ = 14067324.

The previous prime is 21100999. The next prime is 21101027. The reversal of 21101013 is 31010112.

It is an interprime number because it is at equal distance from previous prime (21100999) and next prime (21101027).

It is not a de Polignac number, because 21101013 - 2⁶ = 21100949 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (9).

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21100986 and 21101004.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21101033) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 390733 + ... + 390786.

It is an arithmetic number, because the mean of its divisors is an integer number (3907600).

Almost surely, 2^21101013 is an apocalyptic number.

It is an amenable number.

21101013 is a deficient number, since it is larger than the sum of its proper divisors (10159787).

21101013 is an equidigital number, since it uses as much as digits as its factorization.

21101013 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 781528 (or 781522 counting only the distinct ones).

The product of its (nonzero) digits is 6, while the sum is 9.

The square root of 21101013 is about 4593.5838949561. The cubic root of 21101013 is about 276.3340709022.

Adding to 21101013 its reverse (31010112), we get a palindrome (52111125).

Subtracting 21101013 from its reverse (31010112), we obtain a palindrome (9909099).

The spelling of 21101013 in words is "twenty-one million, one hundred one thousand, thirteen".