21120220987 has 2 divisors, whose sum is σ = 21120220988. Its totient is φ = 21120220986.

The previous prime is 21120220969. The next prime is 21120221009. The reversal of 21120220987 is 78902202112.

It is a weak prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21120220987 is a prime.

It is not a weakly prime, because it can be changed into another prime (21120220907) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10560110493 + 10560110494.

It is an arithmetic number, because the mean of its divisors is an integer number (10560110494).

Almost surely, 2^21120220987 is an apocalyptic number.

21120220987 is a deficient number, since it is larger than the sum of its proper divisors (1).

21120220987 is an equidigital number, since it uses as much as digits as its factorization.

21120220987 is an evil number, because the sum of its binary digits is even.

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

The spelling of 21120220987 in words is "twenty-one billion, one hundred twenty million, two hundred twenty thousand, nine hundred eighty-seven".