21650000 has 60 divisors (see below), whose sum is σ = 52551324. Its totient is φ = 8640000.

The previous prime is 21649967. The next prime is 21650011. The reversal of 21650000 is 5612.

It can be written as a sum of positive squares in 6 ways, for example, as 20720704 + 929296 = 4552^2 + 964^2 .

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 49784 + ... + 50216.

Almost surely, 2^21650000 is an apocalyptic number.

21650000 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 21650000, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (26275662).

21650000 is an abundant number, since it is smaller than the sum of its proper divisors (30901324).

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

21650000 is an frugal number, since it uses more digits than its factorization.

21650000 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 466 (or 440 counting only the distinct ones).

The product of its (nonzero) digits is 60, while the sum is 14.

The square root of 21650000 is about 4652.9560496527. The cubic root of 21650000 is about 278.7100527927.

Adding to 21650000 its reverse (5612), we get a palindrome (21655612).

The spelling of 21650000 in words is "twenty-one million, six hundred fifty thousand".