21308658 has 16 divisors (see below), whose sum is σ = 48705600. Its totient is φ = 6088176.

The previous prime is 21308653. The next prime is 21308659. The reversal of 21308658 is 85680312.

It is a happy number.

It is not an unprimeable number, because it can be changed into a prime (21308653) by changing a digit.

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 7 ways as a sum of consecutive naturals, for example, 253633 + ... + 253716.

It is an arithmetic number, because the mean of its divisors is an integer number (3044100).

Almost surely, 2^21308658 is an apocalyptic number.

21308658 is an abundant number, since it is smaller than the sum of its proper divisors (27396942).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21308658 is a wasteful number, since it uses less digits than its factorization.

21308658 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 507361.

The product of its (nonzero) digits is 11520, while the sum is 33.

The square root of 21308658 is about 4616.1301974706. The cubic root of 21308658 is about 277.2375377328.

The spelling of 21308658 in words is "twenty-one million, three hundred eight thousand, six hundred fifty-eight".