21718916 has 6 divisors (see below), whose sum is σ = 38008110. Its totient is φ = 10859456.

The previous prime is 21718897. The next prime is 21718943. The reversal of 21718916 is 61981712.

It can be written as a sum of positive squares in only one way, i.e., 19009600 + 2709316 = 4360^2 + 1646^2 .

It is a super-2 number, since 2×21718916² = 943422624430112, which contains 22 as substring.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 2714861 + ... + 2714868.

It is an arithmetic number, because the mean of its divisors is an integer number (6334685).

Almost surely, 2^21718916 is an apocalyptic number.

It is an amenable number.

21718916 is a deficient number, since it is larger than the sum of its proper divisors (16289194).

21718916 is a wasteful number, since it uses less digits than its factorization.

21718916 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5429733 (or 5429731 counting only the distinct ones).

The product of its digits is 6048, while the sum is 35.

The square root of 21718916 is about 4660.3557804099. The cubic root of 21718916 is about 279.0054683049.

The spelling of 21718916 in words is "twenty-one million, seven hundred eighteen thousand, nine hundred sixteen".