221020542 has 64 divisors (see below), whose sum is σ = 513000000. Its totient is φ = 70447104.

The previous prime is 221020537. The next prime is 221020543. The reversal of 221020542 is 245020122.

221020542 is a `hidden beast` number, since 22 + 102 + 0 + 542 = 666.

221020542 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a Harshad number since it is a multiple of its sum of digits (18).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (221020543) 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, 176334 + ... + 177582.

It is an arithmetic number, because the mean of its divisors is an integer number (8015625).

Almost surely, 2^221020542 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 221020542, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (256500000).

221020542 is an abundant number, since it is smaller than the sum of its proper divisors (291979458).

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

221020542 is a wasteful number, since it uses less digits than its factorization.

221020542 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1402 (or 1396 counting only the distinct ones).

The product of its (nonzero) digits is 320, while the sum is 18.

The square root of 221020542 is about 14866.7596334911. The cubic root of 221020542 is about 604.6130914151.

Adding to 221020542 its reverse (245020122), we get a palindrome (466040664).

The spelling of 221020542 in words is "two hundred twenty-one million, twenty thousand, five hundred forty-two".