21531512 has 8 divisors (see below), whose sum is σ = 40371600. Its totient is φ = 10765752.

The previous prime is 21531493. The next prime is 21531527. The reversal of 21531512 is 21513512.

It is a happy number.

It is a tau number, because it is divible by the number of its divisors (8).

It is a super-2 number, since 2×21531512² = 927212018012288, which contains 22 as substring.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1345712 + ... + 1345727.

It is an arithmetic number, because the mean of its divisors is an integer number (5046450).

Almost surely, 2^21531512 is an apocalyptic number.

It is an amenable number.

21531512 is a deficient number, since it is larger than the sum of its proper divisors (18840088).

21531512 is a wasteful number, since it uses less digits than its factorization.

21531512 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2691445 (or 2691441 counting only the distinct ones).

The product of its digits is 300, while the sum is 20.

The square root of 21531512 is about 4640.2060299086. The cubic root of 21531512 is about 278.2006728735.

The spelling of 21531512 in words is "twenty-one million, five hundred thirty-one thousand, five hundred twelve".