61221509 has 4 divisors (see below), whose sum is σ = 61293804. Its totient is φ = 61149216.

The previous prime is 61221473. The next prime is 61221521. The reversal of 61221509 is 90512216.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 52519009 + 8702500 = 7247^2 + 2950^2 .

It is a cyclic number.

It is not a de Polignac number, because 61221509 - 2²⁴ = 44444293 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (61221529) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 34862 + ... + 36575.

It is an arithmetic number, because the mean of its divisors is an integer number (15323451).

Almost surely, 2^61221509 is an apocalyptic number.

It is an amenable number.

61221509 is a deficient number, since it is larger than the sum of its proper divisors (72295).

61221509 is an equidigital number, since it uses as much as digits as its factorization.

61221509 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 72294.

The product of its (nonzero) digits is 1080, while the sum is 26.

The square root of 61221509 is about 7824.4174863053. The cubic root of 61221509 is about 394.1256288124.

The spelling of 61221509 in words is "sixty-one million, two hundred twenty-one thousand, five hundred nine".