21351034521 has 24 divisors (see below), whose sum is σ = 32494723040. Its totient is φ = 13471920000.

The previous prime is 21351034517. The next prime is 21351034531. The reversal of 21351034521 is 12543015312.

21351034521 is a `hidden beast` number, since 2 + 1 + 35 + 103 + 4 + 521 = 666.

It is not a de Polignac number, because 21351034521 - 2² = 21351034517 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21351034531) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 120321 + ... + 239121.

Almost surely, 2^21351034521 is an apocalyptic number.

It is an amenable number.

21351034521 is a deficient number, since it is larger than the sum of its proper divisors (11143688519).

21351034521 is a wasteful number, since it uses less digits than its factorization.

21351034521 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 119877 (or 119874 counting only the distinct ones).

The product of its (nonzero) digits is 3600, while the sum is 27.

Adding to 21351034521 its reverse (12543015312), we get a palindrome (33894049833).

The spelling of 21351034521 in words is "twenty-one billion, three hundred fifty-one million, thirty-four thousand, five hundred twenty-one".