221506770 has 64 divisors (see below), whose sum is σ = 574926336. Its totient is φ = 54405120.

The previous prime is 221506763. The next prime is 221506777. The reversal of 221506770 is 77605122.

It is an interprime number because it is at equal distance from previous prime (221506763) and next prime (221506777).

It is a Harshad number since it is a multiple of its sum of digits (30).

It is not an unprimeable number, because it can be changed into a prime (221506777) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 19350 + ... + 28590.

It is an arithmetic number, because the mean of its divisors is an integer number (8983224).

Almost surely, 2^221506770 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 221506770, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (287463168).

221506770 is an abundant number, since it is smaller than the sum of its proper divisors (353419566).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

221506770 is a wasteful number, since it uses less digits than its factorization.

221506770 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9315.

The product of its (nonzero) digits is 5880, while the sum is 30.

The square root of 221506770 is about 14883.1035069975. The cubic root of 221506770 is about 605.0561339441.

It can be divided in two parts, 22150 and 6770, that added together give a triangular number (28920 = T₂₄₀).

The spelling of 221506770 in words is "two hundred twenty-one million, five hundred six thousand, seven hundred seventy".