61644421 has 2 divisors, whose sum is σ = 61644422. Its totient is φ = 61644420.

The previous prime is 61644409. The next prime is 61644449. The reversal of 61644421 is 12444616.

It is an a-pointer prime, because the next prime (61644449) can be obtained adding 61644421 to its sum of digits (28).

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 36784225 + 24860196 = 6065^2 + 4986^2 .

It is a cyclic number.

It is not a de Polignac number, because 61644421 - 2⁵ = 61644389 is a prime.

It is a Chen prime.

It is a self number, because there is not a number n which added to its sum of digits gives 61644421.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (61644491) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 30822210 + 30822211.

It is an arithmetic number, because the mean of its divisors is an integer number (30822211).

Almost surely, 2^61644421 is an apocalyptic number.

It is an amenable number.

61644421 is a deficient number, since it is larger than the sum of its proper divisors (1).

61644421 is an equidigital number, since it uses as much as digits as its factorization.

61644421 is an evil number, because the sum of its binary digits is even.

The product of its digits is 4608, while the sum is 28.

The square root of 61644421 is about 7851.3961178888. The cubic root of 61644421 is about 395.0310737718.

It can be divided in two parts, 6164 and 4421, that added together give a triangular number (10585 = T₁₄₅).

The spelling of 61644421 in words is "sixty-one million, six hundred forty-four thousand, four hundred twenty-one".