21720349527 has 4 divisors (see below), whose sum is σ = 28960466040. Its totient is φ = 14480233016.

The previous prime is 21720349481. The next prime is 21720349531. The reversal of 21720349527 is 72594302712.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 21720349527 - 2⁶ = 21720349463 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21720349577) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3620058252 + ... + 3620058257.

It is an arithmetic number, because the mean of its divisors is an integer number (7240116510).

Almost surely, 2^21720349527 is an apocalyptic number.

21720349527 is a deficient number, since it is larger than the sum of its proper divisors (7240116513).

21720349527 is an equidigital number, since it uses as much as digits as its factorization.

21720349527 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7240116512.

The product of its (nonzero) digits is 211680, while the sum is 42.

The spelling of 21720349527 in words is "twenty-one billion, seven hundred twenty million, three hundred forty-nine thousand, five hundred twenty-seven".