21020078 has 8 divisors (see below), whose sum is σ = 31572072. Its totient is φ = 10496056.

The previous prime is 21020059. The next prime is 21020081. The reversal of 21020078 is 87002012.

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

It is a Curzon number.

It is a congruent 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 3 ways as a sum of consecutive naturals, for example, 5000 + ... + 8187.

It is an arithmetic number, because the mean of its divisors is an integer number (3946509).

Almost surely, 2^21020078 is an apocalyptic number.

21020078 is a deficient number, since it is larger than the sum of its proper divisors (10551994).

21020078 is a wasteful number, since it uses less digits than its factorization.

21020078 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 13986.

The product of its (nonzero) digits is 224, while the sum is 20.

The square root of 21020078 is about 4584.7658609792. The cubic root of 21020078 is about 275.9803161065.

The spelling of 21020078 in words is "twenty-one million, twenty thousand, seventy-eight".