21542100 has 36 divisors (see below), whose sum is σ = 62329344. Its totient is φ = 5744480.

The previous prime is 21542093. The next prime is 21542119. The reversal of 21542100 is 124512.

It is a Harshad number since it is a multiple of its sum of digits (15).

It is a self number, because there is not a number n which added to its sum of digits gives 21542100.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 35604 + ... + 36203.

Almost surely, 2^21542100 is an apocalyptic number.

21542100 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21542100 is an abundant number, since it is smaller than the sum of its proper divisors (40787244).

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

21542100 is a wasteful number, since it uses less digits than its factorization.

21542100 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 71824 (or 71817 counting only the distinct ones).

The product of its (nonzero) digits is 80, while the sum is 15.

The square root of 21542100 is about 4641.3467873022. The cubic root of 21542100 is about 278.2462666066.

Adding to 21542100 its reverse (124512), we get a palindrome (21666612).

The spelling of 21542100 in words is "twenty-one million, five hundred forty-two thousand, one hundred".