21078807 has 8 divisors (see below), whose sum is σ = 28152960. Its totient is φ = 14028600.

The previous prime is 21078781. The next prime is 21078829. The reversal of 21078807 is 70887012.

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

It is not a de Polignac number, because 21078807 - 2¹⁶ = 21013271 is a prime.

It is a super-2 number, since 2×21078807² = 888632209086498, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21078857) 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, 3819 + ... + 7532.

It is an arithmetic number, because the mean of its divisors is an integer number (3519120).

Almost surely, 2^21078807 is an apocalyptic number.

21078807 is a deficient number, since it is larger than the sum of its proper divisors (7074153).

21078807 is a wasteful number, since it uses less digits than its factorization.

21078807 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 11973.

The product of its (nonzero) digits is 6272, while the sum is 33.

The square root of 21078807 is about 4591.1661917208. The cubic root of 21078807 is about 276.2371019687.

The spelling of 21078807 in words is "twenty-one million, seventy-eight thousand, eight hundred seven".