21350431 has 4 divisors (see below), whose sum is σ = 21439264. Its totient is φ = 21261600.

The previous prime is 21350401. The next prime is 21350437. The reversal of 21350431 is 13405312.

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 21350431 - 2¹³ = 21342239 is a prime.

It is a super-2 number, since 2×21350431² = 911681807771522, 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 = 21350399 and 21350408.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21350437) 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, 44055 + ... + 44536.

It is an arithmetic number, because the mean of its divisors is an integer number (5359816).

Almost surely, 2^21350431 is an apocalyptic number.

21350431 is a deficient number, since it is larger than the sum of its proper divisors (88833).

21350431 is an equidigital number, since it uses as much as digits as its factorization.

21350431 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 88832.

The product of its (nonzero) digits is 360, while the sum is 19.

The square root of 21350431 is about 4620.6526595277. The cubic root of 21350431 is about 277.4185828298.

Adding to 21350431 its reverse (13405312), we get a palindrome (34755743).

The spelling of 21350431 in words is "twenty-one million, three hundred fifty thousand, four hundred thirty-one".