21187007 has 4 divisors (see below), whose sum is σ = 21282240. Its totient is φ = 21091776.

The previous prime is 21186983. The next prime is 21187013. The reversal of 21187007 is 70078112.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 21187007 - 2⁶ = 21186943 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 (21187027) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 47282 + ... + 47727.

It is an arithmetic number, because the mean of its divisors is an integer number (5320560).

Almost surely, 2^21187007 is an apocalyptic number.

21187007 is a deficient number, since it is larger than the sum of its proper divisors (95233).

21187007 is an equidigital number, since it uses as much as digits as its factorization.

21187007 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 95232.

The product of its (nonzero) digits is 784, while the sum is 26.

The square root of 21187007 is about 4602.9346073999. The cubic root of 21187007 is about 276.7089480710.

The spelling of 21187007 in words is "twenty-one million, one hundred eighty-seven thousand, seven".