21990718 has 8 divisors (see below), whose sum is σ = 34050240. Its totient is φ = 10640640.

The previous prime is 21990713. The next prime is 21990721. The reversal of 21990718 is 81709912.

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

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21990713) 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, 177283 + ... + 177406.

It is an arithmetic number, because the mean of its divisors is an integer number (4256280).

Almost surely, 2^21990718 is an apocalyptic number.

21990718 is a deficient number, since it is larger than the sum of its proper divisors (12059522).

21990718 is a wasteful number, since it uses less digits than its factorization.

21990718 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 354722.

The product of its (nonzero) digits is 9072, while the sum is 37.

The square root of 21990718 is about 4689.4261909108. The cubic root of 21990718 is about 280.1645206600.

The spelling of 21990718 in words is "twenty-one million, nine hundred ninety thousand, seven hundred eighteen".