21387005 has 8 divisors (see below), whose sum is σ = 25689312. Its totient is φ = 17093008.

The previous prime is 21387001. The next prime is 21387059. The reversal of 21387005 is 50078312.

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

It is a cyclic number.

It is not a de Polignac number, because 21387005 - 2² = 21387001 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 (21387001) 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, 8414 + ... + 10656.

It is an arithmetic number, because the mean of its divisors is an integer number (3211164).

Almost surely, 2^21387005 is an apocalyptic number.

It is an amenable number.

21387005 is a deficient number, since it is larger than the sum of its proper divisors (4302307).

21387005 is a wasteful number, since it uses less digits than its factorization.

21387005 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4155.

The product of its (nonzero) digits is 1680, while the sum is 26.

The square root of 21387005 is about 4624.6086320899. The cubic root of 21387005 is about 277.5769015557.

The spelling of 21387005 in words is "twenty-one million, three hundred eighty-seven thousand, five".