21220718 has 4 divisors (see below), whose sum is σ = 31831080. Its totient is φ = 10610358.

The previous prime is 21220711. The next prime is 21220733. The reversal of 21220718 is 81702212.

It is a semiprime because it is the product of two primes.

It is a junction number, because it is equal to n+sod(n) for n = 21220693 and 21220702.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21220711) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5305178 + ... + 5305181.

It is an arithmetic number, because the mean of its divisors is an integer number (7957770).

Almost surely, 2^21220718 is an apocalyptic number.

21220718 is a deficient number, since it is larger than the sum of its proper divisors (10610362).

21220718 is a wasteful number, since it uses less digits than its factorization.

21220718 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10610361.

The product of its (nonzero) digits is 448, while the sum is 23.

The square root of 21220718 is about 4606.5950549185. The cubic root of 21220718 is about 276.8556290429.

The spelling of 21220718 in words is "twenty-one million, two hundred twenty thousand, seven hundred eighteen".