21158117540 has 48 divisors (see below), whose sum is σ = 52530508800. Its totient is φ = 7004065152.

The previous prime is 21158117521. The next prime is 21158117543. The reversal of 21158117540 is 4571185112.

It is a Harshad number since it is a multiple of its sum of digits (35).

It is a self number, because there is not a number n which added to its sum of digits gives 21158117540.

It is not an unprimeable number, because it can be changed into a prime (21158117543) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 2601620 + ... + 2609739.

It is an arithmetic number, because the mean of its divisors is an integer number (1094385600).

Almost surely, 2^21158117540 is an apocalyptic number.

21158117540 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21158117540 is an abundant number, since it is smaller than the sum of its proper divisors (31372391260).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21158117540 is a wasteful number, since it uses less digits than its factorization.

21158117540 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5211404 (or 5211402 counting only the distinct ones).

The product of its (nonzero) digits is 11200, while the sum is 35.

The spelling of 21158117540 in words is "twenty-one billion, one hundred fifty-eight million, one hundred seventeen thousand, five hundred forty".