21489390 has 48 divisors (see below), whose sum is σ = 60173568. Its totient is φ = 5289408.

The previous prime is 21489389. The next prime is 21489401. The reversal of 21489390 is 9398412.

It is a Curzon number.

It is a congruent number.

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, 8014 + ... + 10353.

It is an arithmetic number, because the mean of its divisors is an integer number (1253616).

Almost surely, 2^21489390 is an apocalyptic number.

21489390 is an abundant number, since it is smaller than the sum of its proper divisors (38684178).

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

21489390 is a wasteful number, since it uses less digits than its factorization.

21489390 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 18393 (or 18390 counting only the distinct ones).

The product of its (nonzero) digits is 15552, while the sum is 36.

The square root of 21489390 is about 4635.6650008386. The cubic root of 21489390 is about 278.0191402035.

The spelling of 21489390 in words is "twenty-one million, four hundred eighty-nine thousand, three hundred ninety".