21137787406 has 4 divisors (see below), whose sum is σ = 31706681112. Its totient is φ = 10568893702.

The previous prime is 21137787401. The next prime is 21137787439. The reversal of 21137787406 is 60478773112.

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

It is a super-3 number, since 3×21137787406³ (a number of 32 digits) contains 333 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21137787401) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5284446850 + ... + 5284446853.

It is an arithmetic number, because the mean of its divisors is an integer number (7926670278).

Almost surely, 2^21137787406 is an apocalyptic number.

21137787406 is a deficient number, since it is larger than the sum of its proper divisors (10568893706).

21137787406 is a wasteful number, since it uses less digits than its factorization.

21137787406 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10568893705.

The product of its (nonzero) digits is 395136, while the sum is 46.

The spelling of 21137787406 in words is "twenty-one billion, one hundred thirty-seven million, seven hundred eighty-seven thousand, four hundred six".