221761540 has 288 divisors, whose sum is σ = 675682560. Its totient is φ = 59304960.

The previous prime is 221761499. The next prime is 221761541. The reversal of 221761540 is 45167122.

It is a Harshad number since it is a multiple of its sum of digits (28).

It is a junction number, because it is equal to n+sod(n) for n = 221761499 and 221761508.

It is not an unprimeable number, because it can be changed into a prime (221761541) by changing a digit.

It is a polite number, since it can be written in 95 ways as a sum of consecutive naturals, for example, 4184154 + ... + 4184206.

It is an arithmetic number, because the mean of its divisors is an integer number (2346120).

Almost surely, 2^221761540 is an apocalyptic number.

221761540 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 221761540, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (337841280).

221761540 is an abundant number, since it is smaller than the sum of its proper divisors (453921020).

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

221761540 is a wasteful number, since it uses less digits than its factorization.

221761540 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 123 (or 110 counting only the distinct ones).

The product of its (nonzero) digits is 3360, while the sum is 28.

The square root of 221761540 is about 14891.6600820728. The cubic root of 221761540 is about 605.2880171344.

It can be divided in two parts, 22176 and 1540, that added together give a square (23716 = 154²).

The spelling of 221761540 in words is "two hundred twenty-one million, seven hundred sixty-one thousand, five hundred forty".