21355487 has 4 divisors (see below), whose sum is σ = 22479480. Its totient is φ = 20231496.

The previous prime is 21355483. The next prime is 21355501. The reversal of 21355487 is 78455312.

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 21355487 - 2² = 21355483 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 (21355483) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 561968 + ... + 562005.

It is an arithmetic number, because the mean of its divisors is an integer number (5619870).

Almost surely, 2^21355487 is an apocalyptic number.

21355487 is a deficient number, since it is larger than the sum of its proper divisors (1123993).

21355487 is a wasteful number, since it uses less digits than its factorization.

21355487 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1123992.

The product of its digits is 33600, while the sum is 35.

The square root of 21355487 is about 4621.1997359993. The cubic root of 21355487 is about 277.4404796188.

The spelling of 21355487 in words is "twenty-one million, three hundred fifty-five thousand, four hundred eighty-seven".