21126918987 has 64 divisors (see below), whose sum is σ = 32580817920. Its totient is φ = 13520851200.

The previous prime is 21126918973. The next prime is 21126919001. The reversal of 21126918987 is 78981962112.

It is a happy number.

It is an interprime number because it is at equal distance from previous prime (21126918973) and next prime (21126919001).

It is not a de Polignac number, because 21126918987 - 2¹⁴ = 21126902603 is a prime.

It is a super-2 number, since 2×21126918987² (a number of 21 digits) contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (21126918937) by changing a digit.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 20491162 + ... + 20492192.

It is an arithmetic number, because the mean of its divisors is an integer number (509075280).

Almost surely, 2^21126918987 is an apocalyptic number.

21126918987 is a gapful number since it is divisible by the number (27) formed by its first and last digit.

21126918987 is a deficient number, since it is larger than the sum of its proper divisors (11453898933).

21126918987 is a wasteful number, since it uses less digits than its factorization.

21126918987 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1361 (or 1355 counting only the distinct ones).

The product of its digits is 870912, while the sum is 54.

The spelling of 21126918987 in words is "twenty-one billion, one hundred twenty-six million, nine hundred eighteen thousand, nine hundred eighty-seven".