21531240566 has 32 divisors (see below), whose sum is σ = 35916278688. Its totient is φ = 9597303040.

The previous prime is 21531240491. The next prime is 21531240581. The reversal of 21531240566 is 66504213512.

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, 3136610 + ... + 3143466.

It is an arithmetic number, because the mean of its divisors is an integer number (1122383709).

Almost surely, 2^21531240566 is an apocalyptic number.

21531240566 is a deficient number, since it is larger than the sum of its proper divisors (14385038122).

21531240566 is a wasteful number, since it uses less digits than its factorization.

21531240566 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9616.

The product of its (nonzero) digits is 43200, while the sum is 35.

The spelling of 21531240566 in words is "twenty-one billion, five hundred thirty-one million, two hundred forty thousand, five hundred sixty-six".