21150000 has 180 divisors, whose sum is σ = 75557664. Its totient is φ = 5520000.

The previous prime is 21149993. The next prime is 21150001. The reversal of 21150000 is 5112.

It is a happy number.

It is a tau number, because it is divible by the number of its divisors (180).

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

It is not an unprimeable number, because it can be changed into a prime (21150001) by changing a digit.

It is a polite number, since it can be written in 35 ways as a sum of consecutive naturals, for example, 449977 + ... + 450023.

Almost surely, 2^21150000 is an apocalyptic number.

21150000 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 21150000, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (37778832).

21150000 is an abundant number, since it is smaller than the sum of its proper divisors (54407664).

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

21150000 is an equidigital number, since it uses as much as digits as its factorization.

21150000 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 86 (or 57 counting only the distinct ones).

The product of its (nonzero) digits is 10, while the sum is 9.

The square root of 21150000 is about 4598.9129150268. The cubic root of 21150000 is about 276.5477465078.

Adding to 21150000 its reverse (5112), we get a palindrome (21155112).

The spelling of 21150000 in words is "twenty-one million, one hundred fifty thousand".