21340890 has 48 divisors (see below), whose sum is σ = 56440800. Its totient is φ = 5593056.

The previous prime is 21340889. The next prime is 21340931. The reversal of 21340890 is 9804312.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 3301 + ... + 7319.

It is an arithmetic number, because the mean of its divisors is an integer number (1175850).

Almost surely, 2^21340890 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21340890, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (28220400).

21340890 is an abundant number, since it is smaller than the sum of its proper divisors (35099910).

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

21340890 is a wasteful number, since it uses less digits than its factorization.

21340890 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4091 (or 4088 counting only the distinct ones).

The product of its (nonzero) digits is 1728, while the sum is 27.

The square root of 21340890 is about 4619.6201142518. The cubic root of 21340890 is about 277.3772527497.

The spelling of 21340890 in words is "twenty-one million, three hundred forty thousand, eight hundred ninety".