21858461951 has 4 divisors (see below), whose sum is σ = 21878910600. Its totient is φ = 21838013304.

The previous prime is 21858461941. The next prime is 21858461969. The reversal of 21858461951 is 15916485812.

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 21858461951 - 2¹⁰ = 21858460927 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 21858461951.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21858461921) 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, 10222721 + ... + 10224858.

It is an arithmetic number, because the mean of its divisors is an integer number (5469727650).

Almost surely, 2^21858461951 is an apocalyptic number.

21858461951 is a deficient number, since it is larger than the sum of its proper divisors (20448649).

21858461951 is a wasteful number, since it uses less digits than its factorization.

21858461951 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 20448648.

The product of its digits is 691200, while the sum is 50.

The spelling of 21858461951 in words is "twenty-one billion, eight hundred fifty-eight million, four hundred sixty-one thousand, nine hundred fifty-one".