21040386431 has 4 divisors (see below), whose sum is σ = 21193966032. Its totient is φ = 20886806832.

The previous prime is 21040386391. The next prime is 21040386439. The reversal of 21040386431 is 13468304012.

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 21040386431 - 2¹⁰ = 21040385407 is a prime.

It is a super-2 number, since 2×21040386431² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21040386439) 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, 76789595 + ... + 76789868.

It is an arithmetic number, because the mean of its divisors is an integer number (5298491508).

Almost surely, 2^21040386431 is an apocalyptic number.

21040386431 is a deficient number, since it is larger than the sum of its proper divisors (153579601).

21040386431 is a wasteful number, since it uses less digits than its factorization.

21040386431 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 153579600.

The product of its (nonzero) digits is 13824, while the sum is 32.

The spelling of 21040386431 in words is "twenty-one billion, forty million, three hundred eighty-six thousand, four hundred thirty-one".