61809551 has 4 divisors (see below), whose sum is σ = 61836504. Its totient is φ = 61782600.

The previous prime is 61809493. The next prime is 61809563. The reversal of 61809551 is 15590816.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-61809551 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 (61809581) 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, 9680 + ... + 14741.

It is an arithmetic number, because the mean of its divisors is an integer number (15459126).

Almost surely, 2^61809551 is an apocalyptic number.

61809551 is a deficient number, since it is larger than the sum of its proper divisors (26953).

61809551 is a wasteful number, since it uses less digits than its factorization.

61809551 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 26952.

The product of its (nonzero) digits is 10800, while the sum is 35.

The square root of 61809551 is about 7861.9050490323. The cubic root of 61809551 is about 395.3834891265.

The spelling of 61809551 in words is "sixty-one million, eight hundred nine thousand, five hundred fifty-one".