21721262527 has 4 divisors (see below), whose sum is σ = 21830414800. Its totient is φ = 21612110256.

The previous prime is 21721262509. The next prime is 21721262533. The reversal of 21721262527 is 72526212712.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21721262527 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21721262557) 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, 54575838 + ... + 54576235.

It is an arithmetic number, because the mean of its divisors is an integer number (5457603700).

Almost surely, 2^21721262527 is an apocalyptic number.

21721262527 is a deficient number, since it is larger than the sum of its proper divisors (109152273).

21721262527 is a wasteful number, since it uses less digits than its factorization.

21721262527 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 109152272.

The product of its digits is 47040, while the sum is 37.

The spelling of 21721262527 in words is "twenty-one billion, seven hundred twenty-one million, two hundred sixty-two thousand, five hundred twenty-seven".