21466890 has 64 divisors (see below), whose sum is σ = 58608000. Its totient is φ = 5591376.

The previous prime is 21466883. The next prime is 21466897. The reversal of 21466890 is 9866412.

It is an interprime number because it is at equal distance from previous prime (21466883) and next prime (21466897).

It is not an unprimeable number, because it can be changed into a prime (21466897) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 499209 + ... + 499251.

It is an arithmetic number, because the mean of its divisors is an integer number (915750).

Almost surely, 2^21466890 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21466890, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (29304000).

21466890 is an abundant number, since it is smaller than the sum of its proper divisors (37141110).

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

21466890 is an frugal number, since it uses more digits than its factorization.

21466890 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 145 (or 53 counting only the distinct ones).

The product of its (nonzero) digits is 20736, while the sum is 36.

The square root of 21466890 is about 4633.2375289855. The cubic root of 21466890 is about 277.9220750141.

The spelling of 21466890 in words is "twenty-one million, four hundred sixty-six thousand, eight hundred ninety".