21031101 has 24 divisors (see below), whose sum is σ = 37390080. Its totient is φ = 11092896.

The previous prime is 21031097. The next prime is 21031103. The reversal of 21031101 is 10113012.

It is not a de Polignac number, because 21031101 - 2² = 21031097 is a prime.

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

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21031103) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 12021 + ... + 13658.

It is an arithmetic number, because the mean of its divisors is an integer number (1557920).

Almost surely, 2^21031101 is an apocalyptic number.

21031101 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

It is an amenable number.

21031101 is a deficient number, since it is larger than the sum of its proper divisors (16358979).

21031101 is a wasteful number, since it uses less digits than its factorization.

21031101 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 25705 (or 25702 counting only the distinct ones).

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

The square root of 21031101 is about 4585.9678367821. The cubic root of 21031101 is about 276.0285493467.

Adding to 21031101 its reverse (10113012), we get a palindrome (31144113).

The spelling of 21031101 in words is "twenty-one million, thirty-one thousand, one hundred one".