21355823949 has 8 divisors (see below), whose sum is σ = 28477197792. Its totient is φ = 14235833040.

The previous prime is 21355823939. The next prime is 21355823953. The reversal of 21355823949 is 94932855312.

It is a happy number.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 21355823949 - 2⁴ = 21355823933 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21355823939) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 309147 + ... + 371864.

It is an arithmetic number, because the mean of its divisors is an integer number (3559649724).

Almost surely, 2^21355823949 is an apocalyptic number.

It is an amenable number.

21355823949 is a deficient number, since it is larger than the sum of its proper divisors (7121373843).

21355823949 is a wasteful number, since it uses less digits than its factorization.

21355823949 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 691467.

The product of its digits is 2332800, while the sum is 51.

The spelling of 21355823949 in words is "twenty-one billion, three hundred fifty-five million, eight hundred twenty-three thousand, nine hundred forty-nine".