21432031 has 4 divisors (see below), whose sum is σ = 21478392. Its totient is φ = 21385672.

The previous prime is 21432023. The next prime is 21432077. The reversal of 21432031 is 13023412.

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 21432031 - 2³ = 21432023 is a prime.

It is a super-2 number, since 2×21432031² = 918663905569922, 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 = 21431996 and 21432014.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21432091) 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, 22480 + ... + 23413.

It is an arithmetic number, because the mean of its divisors is an integer number (5369598).

Almost surely, 2^21432031 is an apocalyptic number.

21432031 is a deficient number, since it is larger than the sum of its proper divisors (46361).

21432031 is an equidigital number, since it uses as much as digits as its factorization.

21432031 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 46360.

The product of its (nonzero) digits is 144, while the sum is 16.

The square root of 21432031 is about 4629.4741602044. The cubic root of 21432031 is about 277.7715589660.

Adding to 21432031 its reverse (13023412), we get a palindrome (34455443).

The spelling of 21432031 in words is "twenty-one million, four hundred thirty-two thousand, thirty-one".