21571761451 has 4 divisors (see below), whose sum is σ = 21978775872. Its totient is φ = 21164747032.

The previous prime is 21571761427. The next prime is 21571761457. The reversal of 21571761451 is 15416717512.

It is a happy number.

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-21571761451 is a prime.

It is a Smith number, since the sum of its digits (40) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21571761457) 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, 203507131 + ... + 203507236.

It is an arithmetic number, because the mean of its divisors is an integer number (5494693968).

Almost surely, 2^21571761451 is an apocalyptic number.

21571761451 is a deficient number, since it is larger than the sum of its proper divisors (407014421).

21571761451 is an equidigital number, since it uses as much as digits as its factorization.

21571761451 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 407014420.

The product of its digits is 58800, while the sum is 40.

The spelling of 21571761451 in words is "twenty-one billion, five hundred seventy-one million, seven hundred sixty-one thousand, four hundred fifty-one".