21158117551 has 8 divisors (see below), whose sum is σ = 22052685824. Its totient is φ = 20276802360.

The previous prime is 21158117543. The next prime is 21158117581. The reversal of 21158117551 is 15571185112.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21158117551 - 2³ = 21158117543 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21158117551.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21158117501) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 3310011 + ... + 3316396.

It is an arithmetic number, because the mean of its divisors is an integer number (2756585728).

Almost surely, 2^21158117551 is an apocalyptic number.

21158117551 is a deficient number, since it is larger than the sum of its proper divisors (894568273).

21158117551 is a wasteful number, since it uses less digits than its factorization.

21158117551 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6626541.

The product of its digits is 14000, while the sum is 37.

The spelling of 21158117551 in words is "twenty-one billion, one hundred fifty-eight million, one hundred seventeen thousand, five hundred fifty-one".