21770887 has 4 divisors (see below), whose sum is σ = 21785896. Its totient is φ = 21755880.

The previous prime is 21770873. The next prime is 21770893. The reversal of 21770887 is 78807712.

It is a happy number.

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 21770887 - 2²³ = 13382279 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 (21770087) 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 3 ways as a sum of consecutive naturals, for example, 5064 + ... + 8317.

It is an arithmetic number, because the mean of its divisors is an integer number (5446474).

Almost surely, 2^21770887 is an apocalyptic number.

21770887 is a deficient number, since it is larger than the sum of its proper divisors (15009).

21770887 is a wasteful number, since it uses less digits than its factorization.

21770887 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 15008.

The product of its (nonzero) digits is 43904, while the sum is 40.

The square root of 21770887 is about 4665.9283106366. The cubic root of 21770887 is about 279.2278342639.

The spelling of 21770887 in words is "twenty-one million, seven hundred seventy thousand, eight hundred eighty-seven".