21201220987 has 8 divisors (see below), whose sum is σ = 21453391872. Its totient is φ = 20950521000.

The previous prime is 21201220981. The next prime is 21201221021. The reversal of 21201220987 is 78902210212.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21201220987 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21201220981) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 338713 + ... + 396394.

It is an arithmetic number, because the mean of its divisors is an integer number (2681673984).

Almost surely, 2^21201220987 is an apocalyptic number.

21201220987 is a deficient number, since it is larger than the sum of its proper divisors (252170885).

21201220987 is a wasteful number, since it uses less digits than its factorization.

21201220987 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 735449.

The product of its (nonzero) digits is 8064, while the sum is 34.

The spelling of 21201220987 in words is "twenty-one billion, two hundred one million, two hundred twenty thousand, nine hundred eighty-seven".