221156831 has 4 divisors (see below), whose sum is σ = 252750672. Its totient is φ = 189562992.

The previous prime is 221156809. The next prime is 221156833. The reversal of 221156831 is 138651122.

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 221156831 - 2¹⁰ = 221155807 is a prime.

It is a super-2 number, since 2×221156831² = 97820687795925122, 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 = 221156794 and 221156803.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (221156833) 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, 15796910 + ... + 15796923.

It is an arithmetic number, because the mean of its divisors is an integer number (63187668).

Almost surely, 2^221156831 is an apocalyptic number.

221156831 is a deficient number, since it is larger than the sum of its proper divisors (31593841).

221156831 is an equidigital number, since it uses as much as digits as its factorization.

221156831 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 31593840.

The product of its digits is 2880, while the sum is 29.

The square root of 221156831 is about 14871.3426091930. The cubic root of 221156831 is about 604.7373410758.

The spelling of 221156831 in words is "two hundred twenty-one million, one hundred fifty-six thousand, eight hundred thirty-one".