21202121987 has 2 divisors, whose sum is σ = 21202121988. Its totient is φ = 21202121986.

The previous prime is 21202121981. The next prime is 21202122023. The reversal of 21202121987 is 78912120212.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21202121987 - 2¹² = 21202117891 is a prime.

It is not a weakly prime, because it can be changed into another prime (21202121981) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10601060993 + 10601060994.

It is an arithmetic number, because the mean of its divisors is an integer number (10601060994).

Almost surely, 2^21202121987 is an apocalyptic number.

21202121987 is a deficient number, since it is larger than the sum of its proper divisors (1).

21202121987 is an equidigital number, since it uses as much as digits as its factorization.

21202121987 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 8064, while the sum is 35.

The spelling of 21202121987 in words is "twenty-one billion, two hundred two million, one hundred twenty-one thousand, nine hundred eighty-seven".