221256731 has 2 divisors, whose sum is σ = 221256732. Its totient is φ = 221256730.

The previous prime is 221256677. The next prime is 221256743. The reversal of 221256731 is 137652122.

It is a happy number.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 221256731 - 2¹⁰ = 221255707 is a prime.

It is a super-2 number, since 2×221256731² = 97909082025612722, which contains 22 as substring.

It is a Chen prime.

It is a junction number, because it is equal to n+sod(n) for n = 221256694 and 221256703.

It is not a weakly prime, because it can be changed into another prime (221216731) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 110628365 + 110628366.

It is an arithmetic number, because the mean of its divisors is an integer number (110628366).

Almost surely, 2^221256731 is an apocalyptic number.

221256731 is a deficient number, since it is larger than the sum of its proper divisors (1).

221256731 is an equidigital number, since it uses as much as digits as its factorization.

221256731 is an evil number, because the sum of its binary digits is even.

The product of its digits is 5040, while the sum is 29.

The square root of 221256731 is about 14874.7010390125. The cubic root of 221256731 is about 604.8283838075.

The spelling of 221256731 in words is "two hundred twenty-one million, two hundred fifty-six thousand, seven hundred thirty-one".