21078663 has 8 divisors (see below), whose sum is σ = 28284528. Its totient is φ = 13962624.

The previous prime is 21078637. The next prime is 21078703. The reversal of 21078663 is 36687012.

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

It is not a de Polignac number, because 21078663 - 2¹⁶ = 21013127 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21028663) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 21906 + ... + 22847.

It is an arithmetic number, because the mean of its divisors is an integer number (3535566).

Almost surely, 2^21078663 is an apocalyptic number.

21078663 is a deficient number, since it is larger than the sum of its proper divisors (7205865).

21078663 is a wasteful number, since it uses less digits than its factorization.

21078663 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 44913.

The product of its (nonzero) digits is 12096, while the sum is 33.

The square root of 21078663 is about 4591.1505094039. The cubic root of 21078663 is about 276.2364729288.

The spelling of 21078663 in words is "twenty-one million, seventy-eight thousand, six hundred sixty-three".