21251545671 has 4 divisors (see below), whose sum is σ = 28335394232. Its totient is φ = 14167697112.

The previous prime is 21251545597. The next prime is 21251545697. The reversal of 21251545671 is 17654515212.

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

It is not a de Polignac number, because 21251545671 - 2¹³ = 21251537479 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 (21251545571) 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, 3541924276 + ... + 3541924281.

It is an arithmetic number, because the mean of its divisors is an integer number (7083848558).

Almost surely, 2^21251545671 is an apocalyptic number.

21251545671 is a deficient number, since it is larger than the sum of its proper divisors (7083848561).

21251545671 is an equidigital number, since it uses as much as digits as its factorization.

21251545671 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7083848560.

The product of its digits is 84000, while the sum is 39.

The spelling of 21251545671 in words is "twenty-one billion, two hundred fifty-one million, five hundred forty-five thousand, six hundred seventy-one".