21161261510 has 32 divisors (see below), whose sum is σ = 38202239520. Its totient is φ = 8439662592.

The previous prime is 21161261497. The next prime is 21161261567. The reversal of 21161261510 is 1516216112.

It is a self number, because there is not a number n which added to its sum of digits gives 21161261510.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 6397277 + ... + 6400583.

It is an arithmetic number, because the mean of its divisors is an integer number (1193819985).

Almost surely, 2^21161261510 is an apocalyptic number.

21161261510 is a deficient number, since it is larger than the sum of its proper divisors (17040978010).

21161261510 is a wasteful number, since it uses less digits than its factorization.

21161261510 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5000.

The product of its (nonzero) digits is 720, while the sum is 26.

Adding to 21161261510 its reverse (1516216112), we get a palindrome (22677477622).

The spelling of 21161261510 in words is "twenty-one billion, one hundred sixty-one million, two hundred sixty-one thousand, five hundred ten".