64219861 has 2 divisors, whose sum is σ = 64219862. Its totient is φ = 64219860.

The previous prime is 64219853. The next prime is 64219877. The reversal of 64219861 is 16891246.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 43151761 + 21068100 = 6569^2 + 4590^2 .

It is a cyclic number.

It is not a de Polignac number, because 64219861 - 2³ = 64219853 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 64219861.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (64219801) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 32109930 + 32109931.

It is an arithmetic number, because the mean of its divisors is an integer number (32109931).

Almost surely, 2^64219861 is an apocalyptic number.

It is an amenable number.

64219861 is a deficient number, since it is larger than the sum of its proper divisors (1).

64219861 is an equidigital number, since it uses as much as digits as its factorization.

64219861 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 20736, while the sum is 37.

The square root of 64219861 is about 8013.7295312482. The cubic root of 64219861 is about 400.4575202386.

It can be divided in two parts, 642 and 19861, that added together give a triangular number (20503 = T₂₀₂).

The spelling of 64219861 in words is "sixty-four million, two hundred nineteen thousand, eight hundred sixty-one".