21542820751 has 4 divisors (see below), whose sum is σ = 21543118992. Its totient is φ = 21542522512.

The previous prime is 21542820727. The next prime is 21542820757. The reversal of 21542820751 is 15702824512.

It is a happy number.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It is a cyclic number.

It is not a de Polignac number, because 21542820751 - 2⁷ = 21542820623 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21542820751.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21542820757) 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, 35046 + ... + 210508.

It is an arithmetic number, because the mean of its divisors is an integer number (5385779748).

Almost surely, 2^21542820751 is an apocalyptic number.

21542820751 is a deficient number, since it is larger than the sum of its proper divisors (298241).

21542820751 is a wasteful number, since it uses less digits than its factorization.

21542820751 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 298240.

The product of its (nonzero) digits is 44800, while the sum is 37.

The spelling of 21542820751 in words is "twenty-one billion, five hundred forty-two million, eight hundred twenty thousand, seven hundred fifty-one".