61221440 has 112 divisors (see below), whose sum is σ = 168639744. Its totient is φ = 20736000.

The previous prime is 61221389. The next prime is 61221443. The reversal of 61221440 is 4412216.

It is a tau number, because it is divible by the number of its divisors (112).

It is a Harshad number since it is a multiple of its sum of digits (20).

It is not an unprimeable number, because it can be changed into a prime (61221443) 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, 338150 + ... + 338330.

It is an arithmetic number, because the mean of its divisors is an integer number (1505712).

Almost surely, 2^61221440 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 61221440, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (84319872).

61221440 is an abundant number, since it is smaller than the sum of its proper divisors (107418304).

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

61221440 is a wasteful number, since it uses less digits than its factorization.

61221440 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 356 (or 346 counting only the distinct ones).

The product of its (nonzero) digits is 384, while the sum is 20.

The square root of 61221440 is about 7824.4130770301. The cubic root of 61221440 is about 394.1254807453.

Adding to 61221440 its reverse (4412216), we get a palindrome (65633656).

The spelling of 61221440 in words is "sixty-one million, two hundred twenty-one thousand, four hundred forty".