21270787 has 4 divisors (see below), whose sum is σ = 21280336. Its totient is φ = 21261240.

The previous prime is 21270779. The next prime is 21270797. The reversal of 21270787 is 78707212.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It is a cyclic number.

It is not a de Polignac number, because 21270787 - 2³ = 21270779 is a prime.

It is an alternating number because its digits alternate between even and odd.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21270707) 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, 538 + ... + 6544.

It is an arithmetic number, because the mean of its divisors is an integer number (5320084).

Almost surely, 2^21270787 is an apocalyptic number.

21270787 is a deficient number, since it is larger than the sum of its proper divisors (9549).

21270787 is an equidigital number, since it uses as much as digits as its factorization.

21270787 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9548.

The product of its (nonzero) digits is 10976, while the sum is 34.

The square root of 21270787 is about 4612.0263442439. The cubic root of 21270787 is about 277.0731993857.

Adding to 21270787 its reverse (78707212), we get a palindrome (99977999).

The spelling of 21270787 in words is "twenty-one million, two hundred seventy thousand, seven hundred eighty-seven".