21650390 has 8 divisors (see below), whose sum is σ = 38970720. Its totient is φ = 8660152.

The previous prime is 21650389. The next prime is 21650399. The reversal of 21650390 is 9305612.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21650399) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1082510 + ... + 1082529.

It is an arithmetic number, because the mean of its divisors is an integer number (4871340).

Almost surely, 2^21650390 is an apocalyptic number.

21650390 is a deficient number, since it is larger than the sum of its proper divisors (17320330).

21650390 is a wasteful number, since it uses less digits than its factorization.

21650390 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2165046.

The product of its (nonzero) digits is 1620, while the sum is 26.

The square root of 21650390 is about 4652.9979583060. The cubic root of 21650390 is about 278.7117263303.

The spelling of 21650390 in words is "twenty-one million, six hundred fifty thousand, three hundred ninety".