61644551 has 4 divisors (see below), whose sum is σ = 62190192. Its totient is φ = 61098912.

The previous prime is 61644547. The next prime is 61644581. The reversal of 61644551 is 15544616.

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

It is a cyclic number.

It is not a de Polignac number, because 61644551 - 2² = 61644547 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (61644581) 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, 272651 + ... + 272876.

It is an arithmetic number, because the mean of its divisors is an integer number (15547548).

Almost surely, 2^61644551 is an apocalyptic number.

61644551 is a deficient number, since it is larger than the sum of its proper divisors (545641).

61644551 is a wasteful number, since it uses less digits than its factorization.

61644551 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 545640.

The product of its digits is 14400, while the sum is 32.

The square root of 61644551 is about 7851.4043966669. The cubic root of 61644551 is about 395.0313514612.

The spelling of 61644551 in words is "sixty-one million, six hundred forty-four thousand, five hundred fifty-one".