21471431 has 4 divisors (see below), whose sum is σ = 21531600. Its totient is φ = 21411264.

The previous prime is 21471409. The next prime is 21471449. The reversal of 21471431 is 13417412.

It is a happy number.

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 21471431 - 2⁶ = 21471367 is a prime.

It is a super-2 number, since 2×21471431² = 922044698375522, which contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21471397 and 21471406.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21471481) 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, 29546 + ... + 30263.

It is an arithmetic number, because the mean of its divisors is an integer number (5382900).

Almost surely, 2^21471431 is an apocalyptic number.

21471431 is a deficient number, since it is larger than the sum of its proper divisors (60169).

21471431 is an equidigital number, since it uses as much as digits as its factorization.

21471431 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 60168.

The product of its digits is 672, while the sum is 23.

The square root of 21471431 is about 4633.7275491768. The cubic root of 21471431 is about 277.9416703873.

Adding to 21471431 its reverse (13417412), we get a palindrome (34888843).

The spelling of 21471431 in words is "twenty-one million, four hundred seventy-one thousand, four hundred thirty-one".