21155435371 has 12 divisors (see below), whose sum is σ = 24772368720. Its totient is φ = 18013136400.

The previous prime is 21155435339. The next prime is 21155435383. The reversal of 21155435371 is 17353455112.

It is not a de Polignac number, because 21155435371 - 2⁵ = 21155435339 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 21155435371.

It is not an unprimeable number, because it can be changed into a prime (21155435671) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 1422216 + ... + 1437013.

It is an arithmetic number, because the mean of its divisors is an integer number (2064364060).

Almost surely, 2^21155435371 is an apocalyptic number.

21155435371 is a deficient number, since it is larger than the sum of its proper divisors (3616933349).

21155435371 is a wasteful number, since it uses less digits than its factorization.

21155435371 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2859394 (or 2859387 counting only the distinct ones).

The product of its digits is 63000, while the sum is 37.

The spelling of 21155435371 in words is "twenty-one billion, one hundred fifty-five million, four hundred thirty-five thousand, three hundred seventy-one".