21440201987 has 2 divisors, whose sum is σ = 21440201988. Its totient is φ = 21440201986.

The previous prime is 21440201971. The next prime is 21440202029. The reversal of 21440201987 is 78910204412.

It is a happy number.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21440201987 - 2⁴ = 21440201971 is a prime.

It is a super-2 number, since 2×21440201987² (a number of 21 digits) contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 21440201987.

It is not a weakly prime, because it can be changed into another prime (21440201917) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10720100993 + 10720100994.

It is an arithmetic number, because the mean of its divisors is an integer number (10720100994).

Almost surely, 2^21440201987 is an apocalyptic number.

21440201987 is a deficient number, since it is larger than the sum of its proper divisors (1).

21440201987 is an equidigital number, since it uses as much as digits as its factorization.

21440201987 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 32256, while the sum is 38.

The spelling of 21440201987 in words is "twenty-one billion, four hundred forty million, two hundred one thousand, nine hundred eighty-seven".