21155736515 has 8 divisors (see below), whose sum is σ = 25393547328. Its totient is φ = 16920146880.

The previous prime is 21155736509. The next prime is 21155736517. The reversal of 21155736515 is 51563755112.

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

It is not a de Polignac number, because 21155736515 - 2⁶ = 21155736451 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21155736517) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 534266 + ... + 572495.

It is an arithmetic number, because the mean of its divisors is an integer number (3174193416).

Almost surely, 2^21155736515 is an apocalyptic number.

21155736515 is a deficient number, since it is larger than the sum of its proper divisors (4237810813).

21155736515 is a wasteful number, since it uses less digits than its factorization.

21155736515 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1110589.

The product of its digits is 157500, while the sum is 41.

The spelling of 21155736515 in words is "twenty-one billion, one hundred fifty-five million, seven hundred thirty-six thousand, five hundred fifteen".