21782990 has 16 divisors (see below), whose sum is σ = 39264048. Its totient is φ = 8701056.

The previous prime is 21782963. The next prime is 21783011. The reversal of 21782990 is 9928712.

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 7 ways as a sum of consecutive naturals, for example, 10694 + ... + 12566.

It is an arithmetic number, because the mean of its divisors is an integer number (2454003).

Almost surely, 2^21782990 is an apocalyptic number.

21782990 is a deficient number, since it is larger than the sum of its proper divisors (17481058).

21782990 is a wasteful number, since it uses less digits than its factorization.

21782990 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3043.

The product of its (nonzero) digits is 18144, while the sum is 38.

The square root of 21782990 is about 4667.2250856371. The cubic root of 21782990 is about 279.2795680069.

The spelling of 21782990 in words is "twenty-one million, seven hundred eighty-two thousand, nine hundred ninety".