21278007 has 6 divisors (see below), whose sum is σ = 30734912. Its totient is φ = 14185332.

The previous prime is 21277987. The next prime is 21278021. The reversal of 21278007 is 70087212.

It is not a de Polignac number, because 21278007 - 2¹² = 21273911 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21278087) by changing a digit.

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 5 ways as a sum of consecutive naturals, for example, 1182103 + ... + 1182120.

Almost surely, 2^21278007 is an apocalyptic number.

21278007 is a deficient number, since it is larger than the sum of its proper divisors (9456905).

21278007 is a wasteful number, since it uses less digits than its factorization.

21278007 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2364229 (or 2364226 counting only the distinct ones).

The product of its (nonzero) digits is 1568, while the sum is 27.

The square root of 21278007 is about 4612.8090140391. The cubic root of 21278007 is about 277.1045450712.

The spelling of 21278007 in words is "twenty-one million, two hundred seventy-eight thousand, seven".