20130121987 has 4 divisors (see below), whose sum is σ = 20674179376. Its totient is φ = 19586064600.

The previous prime is 20130121969. The next prime is 20130122021. The reversal of 20130121987 is 78912103102.

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

It is a cyclic number.

It is not a de Polignac number, because 20130121987 - 2¹¹ = 20130119939 is a prime.

It is a super-2 number, since 2×20130121987² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20130821987) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 272028639 + ... + 272028712.

It is an arithmetic number, because the mean of its divisors is an integer number (5168544844).

Almost surely, 2^20130121987 is an apocalyptic number.

20130121987 is a deficient number, since it is larger than the sum of its proper divisors (544057389).

20130121987 is an equidigital number, since it uses as much as digits as its factorization.

20130121987 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 544057388.

The product of its (nonzero) digits is 6048, while the sum is 34.

The spelling of 20130121987 in words is "twenty billion, one hundred thirty million, one hundred twenty-one thousand, nine hundred eighty-seven".