21030778 has 8 divisors (see below), whose sum is σ = 31747572. Its totient is φ = 10448256.

The previous prime is 21030767. The next prime is 21030781. The reversal of 21030778 is 87703012.

It is a happy number.

It can be written as a sum of positive squares in 2 ways, for example, as 17447329 + 3583449 = 4177^2 + 1893^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

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 3 ways as a sum of consecutive naturals, for example, 33175 + ... + 33802.

Almost surely, 2^21030778 is an apocalyptic number.

21030778 is a deficient number, since it is larger than the sum of its proper divisors (10716794).

21030778 is a wasteful number, since it uses less digits than its factorization.

21030778 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 67136.

The product of its (nonzero) digits is 2352, while the sum is 28.

The square root of 21030778 is about 4585.9326205255. The cubic root of 21030778 is about 276.0271362383.

The spelling of 21030778 in words is "twenty-one million, thirty thousand, seven hundred seventy-eight".