21407343991 has 16 divisors (see below), whose sum is σ = 23543815680. Its totient is φ = 19302865920.

The previous prime is 21407343983. The next prime is 21407344019. The reversal of 21407343991 is 19934370412.

It is a cyclic number.

It is not a de Polignac number, because 21407343991 - 2³ = 21407343983 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21407343091) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1756866 + ... + 1769008.

It is an arithmetic number, because the mean of its divisors is an integer number (1471488480).

Almost surely, 2^21407343991 is an apocalyptic number.

21407343991 is a deficient number, since it is larger than the sum of its proper divisors (2136471689).

21407343991 is a wasteful number, since it uses less digits than its factorization.

21407343991 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 13446.

The product of its (nonzero) digits is 163296, while the sum is 43.

It can be divided in two parts, 214073 and 43991, that added together give a square (258064 = 508²).

The spelling of 21407343991 in words is "twenty-one billion, four hundred seven million, three hundred forty-three thousand, nine hundred ninety-one".