21431433231566 has 4 divisors (see below), whose sum is σ = 32147149847352. Its totient is φ = 10715716615782.

The previous prime is 21431433231557. The next prime is 21431433231583. The reversal of 21431433231566 is 66513233413412.

It is a happy number.

It is a semiprime because it is the product of two primes.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5357858307890 + ... + 5357858307893.

It is an arithmetic number, because the mean of its divisors is an integer number (8036787461838).

Almost surely, 2^{21431433231566} is an apocalyptic number.

21431433231566 is a deficient number, since it is larger than the sum of its proper divisors (10715716615786).

21431433231566 is a wasteful number, since it uses less digits than its factorization.

21431433231566 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10715716615785.

The product of its digits is 933120, while the sum is 44.

Adding to 21431433231566 its reverse (66513233413412), we get a palindrome (87944666644978).

The spelling of 21431433231566 in words is "twenty-one trillion, four hundred thirty-one billion, four hundred thirty-three million, two hundred thirty-one thousand, five hundred sixty-six".