61691221 has 4 divisors (see below), whose sum is σ = 64373472. Its totient is φ = 59008972.

The previous prime is 61691219. The next prime is 61691239. The reversal of 61691221 is 12219616.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 61691221 - 2¹ = 61691219 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 61691221.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (61691251) 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, 1341091 + ... + 1341136.

It is an arithmetic number, because the mean of its divisors is an integer number (16093368).

Almost surely, 2^61691221 is an apocalyptic number.

It is an amenable number.

61691221 is a deficient number, since it is larger than the sum of its proper divisors (2682251).

61691221 is a wasteful number, since it uses less digits than its factorization.

61691221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2682250.

The product of its digits is 1296, while the sum is 28.

The square root of 61691221 is about 7854.3759141004. The cubic root of 61691221 is about 395.1310167319.

The spelling of 61691221 in words is "sixty-one million, six hundred ninety-one thousand, two hundred twenty-one".