221402431 has 4 divisors (see below), whose sum is σ = 221466600. Its totient is φ = 221338264.

The previous prime is 221402387. The next prime is 221402437. The reversal of 221402431 is 134204122.

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 221402431 - 2⁷ = 221402303 is a prime.

It is a super-2 number, since 2×221402431² = 98038072905419522, 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 = 221402399 and 221402408.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (221402437) 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, 26596 + ... + 33913.

It is an arithmetic number, because the mean of its divisors is an integer number (55366650).

Almost surely, 2^221402431 is an apocalyptic number.

221402431 is a deficient number, since it is larger than the sum of its proper divisors (64169).

221402431 is an equidigital number, since it uses as much as digits as its factorization.

221402431 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 64168.

The product of its (nonzero) digits is 384, while the sum is 19.

The square root of 221402431 is about 14879.5978104249. The cubic root of 221402431 is about 604.9611167324.

Adding to 221402431 its reverse (134204122), we get a palindrome (355606553).

The spelling of 221402431 in words is "two hundred twenty-one million, four hundred two thousand, four hundred thirty-one".