21901321587 has 4 divisors (see below), whose sum is σ = 29201762120. Its totient is φ = 14600881056.

The previous prime is 21901321529. The next prime is 21901321597. The reversal of 21901321587 is 78512310912.

It is a happy number.

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

It is not a de Polignac number, because 21901321587 - 2⁶ = 21901321523 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21901321517) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3650220262 + ... + 3650220267.

It is an arithmetic number, because the mean of its divisors is an integer number (7300440530).

Almost surely, 2^21901321587 is an apocalyptic number.

21901321587 is a deficient number, since it is larger than the sum of its proper divisors (7300440533).

21901321587 is an equidigital number, since it uses as much as digits as its factorization.

21901321587 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7300440532.

The product of its (nonzero) digits is 30240, while the sum is 39.

The spelling of 21901321587 in words is "twenty-one billion, nine hundred one million, three hundred twenty-one thousand, five hundred eighty-seven".