61655021 has 4 divisors (see below), whose sum is σ = 63158844. Its totient is φ = 60151200.

The previous prime is 61655003. The next prime is 61655047. The reversal of 61655021 is 12055616.

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 29278921 + 32376100 = 5411^2 + 5690^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-61655021 is a prime.

It is a super-2 number, since 2×61655021² = 7602683229020882, which contains 22 as substring.

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 (61655081) 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 in 3 ways as a sum of consecutive naturals, for example, 751850 + ... + 751931.

It is an arithmetic number, because the mean of its divisors is an integer number (15789711).

Almost surely, 2^61655021 is an apocalyptic number.

It is an amenable number.

61655021 is a deficient number, since it is larger than the sum of its proper divisors (1503823).

61655021 is a wasteful number, since it uses less digits than its factorization.

61655021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1503822.

The product of its (nonzero) digits is 1800, while the sum is 26.

The square root of 61655021 is about 7852.0711280528. The cubic root of 61655021 is about 395.0537148551.

The spelling of 61655021 in words is "sixty-one million, six hundred fifty-five thousand, twenty-one".