21716618 has 32 divisors (see below), whose sum is σ = 41126400. Its totient is φ = 8354160.

The previous prime is 21716609. The next prime is 21716627. The reversal of 21716618 is 81661712.

It is a happy number.

It is an interprime number because it is at equal distance from previous prime (21716609) and next prime (21716627).

It is a super-2 number, since 2×21716618² = 943222994715848, which contains 22 as substring.

It is a Curzon number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 11933 + ... + 13631.

It is an arithmetic number, because the mean of its divisors is an integer number (1285200).

Almost surely, 2^21716618 is an apocalyptic number.

21716618 is a deficient number, since it is larger than the sum of its proper divisors (19409782).

21716618 is a wasteful number, since it uses less digits than its factorization.

21716618 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1802.

The product of its digits is 4032, while the sum is 32.

The square root of 21716618 is about 4660.1092261877. The cubic root of 21716618 is about 278.9956277711.

The spelling of 21716618 in words is "twenty-one million, seven hundred sixteen thousand, six hundred eighteen".