21431139 has 8 divisors (see below), whose sum is σ = 28606032. Its totient is φ = 14271840.

The previous prime is 21431131. The next prime is 21431141. The reversal of 21431139 is 93113412.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 21431139 - 2³ = 21431131 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21431131) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 184 + ... + 6549.

It is an arithmetic number, because the mean of its divisors is an integer number (3575754).

Almost surely, 2^21431139 is an apocalyptic number.

21431139 is a deficient number, since it is larger than the sum of its proper divisors (7174893).

21431139 is a wasteful number, since it uses less digits than its factorization.

21431139 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7797.

The product of its digits is 648, while the sum is 24.

The square root of 21431139 is about 4629.3778199667. The cubic root of 21431139 is about 277.7677053000.

The spelling of 21431139 in words is "twenty-one million, four hundred thirty-one thousand, one hundred thirty-nine".