21542500 has 60 divisors (see below), whose sum is σ = 53882752. Its totient is φ = 7380000.

The previous prime is 21542483. The next prime is 21542537. The reversal of 21542500 is 524512.

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 19 ways as a sum of consecutive naturals, for example, 16885 + ... + 18115.

Almost surely, 2^21542500 is an apocalyptic number.

21542500 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21542500, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (26941376).

21542500 is an abundant number, since it is smaller than the sum of its proper divisors (32340252).

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

21542500 is a wasteful number, since it uses less digits than its factorization.

21542500 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1262 (or 1245 counting only the distinct ones).

The product of its (nonzero) digits is 400, while the sum is 19.

The square root of 21542500 is about 4641.3898780430. The cubic root of 21542500 is about 278.2479887819.

The spelling of 21542500 in words is "twenty-one million, five hundred forty-two thousand, five hundred".