61221820 has 48 divisors (see below), whose sum is σ = 140799456. Its totient is φ = 22176000.

The previous prime is 61221817. The next prime is 61221821. The reversal of 61221820 is 2812216.

It is a super-2 number, since 2×61221820² = 7496222488224800, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (22).

It is a junction number, because it is equal to n+sod(n) for n = 61221791 and 61221800.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (61221821) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 92290 + ... + 92950.

It is an arithmetic number, because the mean of its divisors is an integer number (2933322).

Almost surely, 2^61221820 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 61221820, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (70399728).

61221820 is an abundant number, since it is smaller than the sum of its proper divisors (79577636).

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

61221820 is a wasteful number, since it uses less digits than its factorization.

61221820 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1102 (or 1100 counting only the distinct ones).

The product of its (nonzero) digits is 384, while the sum is 22.

The square root of 61221820 is about 7824.4373599640. The cubic root of 61221820 is about 394.1262961861.

The spelling of 61221820 in words is "sixty-one million, two hundred twenty-one thousand, eight hundred twenty".