21618746 has 12 divisors (see below), whose sum is σ = 33587502. Its totient is φ = 10435824.

The previous prime is 21618739. The next prime is 21618787. The reversal of 21618746 is 64781612.

It can be written as a sum of positive squares in 3 ways, for example, as 16605625 + 5013121 = 4075^2 + 2239^2 .

It is a super-2 number, since 2×21618746² = 934740357225032, which contains 22 as substring.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 4745 + ... + 8108.

Almost surely, 2^21618746 is an apocalyptic number.

21618746 is a deficient number, since it is larger than the sum of its proper divisors (11968756).

21618746 is a wasteful number, since it uses less digits than its factorization.

21618746 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 12913 (or 12884 counting only the distinct ones).

The product of its digits is 16128, while the sum is 35.

The square root of 21618746 is about 4649.5963265643. The cubic root of 21618746 is about 278.5758726695.

The spelling of 21618746 in words is "twenty-one million, six hundred eighteen thousand, seven hundred forty-six".