21431427 has 8 divisors (see below), whose sum is σ = 28616016. Its totient is φ = 14267232.

The previous prime is 21431401. The next prime is 21431489. The reversal of 21431427 is 72413412.

It is a happy number.

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

It is not a de Polignac number, because 21431427 - 2¹⁰ = 21430403 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21431397 and 21431406.

It is not an unprimeable number, because it can be changed into a prime (21431497) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 2448 + ... + 6989.

It is an arithmetic number, because the mean of its divisors is an integer number (3577002).

Almost surely, 2^21431427 is an apocalyptic number.

21431427 is a deficient number, since it is larger than the sum of its proper divisors (7184589).

21431427 is an equidigital number, since it uses as much as digits as its factorization.

21431427 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10197.

The product of its digits is 1344, while the sum is 24.

The square root of 21431427 is about 4629.4089255541. The cubic root of 21431427 is about 277.7689495446.

Adding to 21431427 its reverse (72413412), we get a palindrome (93844839).

It can be divided in two parts, 2143 and 1427, that added together give a triangular number (3570 = T₈₄).

The spelling of 21431427 in words is "twenty-one million, four hundred thirty-one thousand, four hundred twenty-seven".