61643381 has 16 divisors (see below), whose sum is σ = 66405504. Its totient is φ = 57081024.

The previous prime is 61643371. The next prime is 61643383. The reversal of 61643381 is 18334616.

It is a cyclic number.

It is not a de Polignac number, because 61643381 - 2¹⁴ = 61626997 is a prime.

It is a super-2 number, since 2×61643381² = 7599812842222322, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (61643383) 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, 155075 + ... + 155471.

It is an arithmetic number, because the mean of its divisors is an integer number (4150344).

Almost surely, 2^61643381 is an apocalyptic number.

It is an amenable number.

61643381 is a deficient number, since it is larger than the sum of its proper divisors (4762123).

61643381 is a wasteful number, since it uses less digits than its factorization.

61643381 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 620.

The product of its digits is 10368, while the sum is 32.

The square root of 61643381 is about 7851.3298873503. The cubic root of 61643381 is about 395.0288522427.

Adding to 61643381 its reverse (18334616), we get a palindrome (79977997).

The spelling of 61643381 in words is "sixty-one million, six hundred forty-three thousand, three hundred eighty-one".