21078516 has 24 divisors (see below), whose sum is σ = 49540960. Its totient is φ = 6975072.

The previous prime is 21078509. The next prime is 21078523. The reversal of 21078516 is 61587012.

It is an interprime number because it is at equal distance from previous prime (21078509) and next prime (21078523).

It is a congruent number.

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 7 ways as a sum of consecutive naturals, for example, 4651 + ... + 7986.

Almost surely, 2^21078516 is an apocalyptic number.

It is an amenable number.

21078516 is an abundant number, since it is smaller than the sum of its proper divisors (28462444).

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

21078516 is a wasteful number, since it uses less digits than its factorization.

21078516 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 12783 (or 12781 counting only the distinct ones).

The product of its (nonzero) digits is 3360, while the sum is 30.

The square root of 21078516 is about 4591.1345003169. The cubic root of 21078516 is about 276.2358307809.

The spelling of 21078516 in words is "twenty-one million, seventy-eight thousand, five hundred sixteen".