21100420 has 24 divisors (see below), whose sum is σ = 48339648. Its totient is φ = 7672800.

The previous prime is 21100411. The next prime is 21100423. The reversal of 21100420 is 2400112.

It is a Harshad number since it is a multiple of its sum of digits (10).

It is a junction number, because it is equal to n+sod(n) for n = 21100397 and 21100406.

It is not an unprimeable number, because it can be changed into a prime (21100423) 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, 47736 + ... + 48175.

It is an arithmetic number, because the mean of its divisors is an integer number (2014152).

Almost surely, 2^21100420 is an apocalyptic number.

21100420 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21100420 is an abundant number, since it is smaller than the sum of its proper divisors (27239228).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21100420 is a wasteful number, since it uses less digits than its factorization.

21100420 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 95931 (or 95929 counting only the distinct ones).

The product of its (nonzero) digits is 16, while the sum is 10.

The square root of 21100420 is about 4593.5193479510. The cubic root of 21100420 is about 276.3314822802.

Adding to 21100420 its reverse (2400112), we get a palindrome (23500532).

The spelling of 21100420 in words is "twenty-one million, one hundred thousand, four hundred twenty".