21565766942 has 16 divisors (see below), whose sum is σ = 35177230800. Its totient is φ = 9874309248.

The previous prime is 21565766941. The next prime is 21565766977. The reversal of 21565766942 is 24966756512.

It is a happy number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21565766941) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 8570192 + ... + 8572707.

It is an arithmetic number, because the mean of its divisors is an integer number (2198576925).

Almost surely, 2^21565766942 is an apocalyptic number.

21565766942 is a deficient number, since it is larger than the sum of its proper divisors (13611463858).

21565766942 is a wasteful number, since it uses less digits than its factorization.

21565766942 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 17142955.

The product of its digits is 5443200, while the sum is 53.

The spelling of 21565766942 in words is "twenty-one billion, five hundred sixty-five million, seven hundred sixty-six thousand, nine hundred forty-two".