61531811 has 4 divisors (see below), whose sum is σ = 67125624. Its totient is φ = 55938000.

The previous prime is 61531793. The next prime is 61531817. The reversal of 61531811 is 11813516.

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-61531811 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (61531817) 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, 2796890 + ... + 2796911.

It is an arithmetic number, because the mean of its divisors is an integer number (16781406).

Almost surely, 2^61531811 is an apocalyptic number.

61531811 is a deficient number, since it is larger than the sum of its proper divisors (5593813).

61531811 is a wasteful number, since it uses less digits than its factorization.

61531811 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5593812.

The product of its digits is 720, while the sum is 26.

The square root of 61531811 is about 7844.2215037568. The cubic root of 61531811 is about 394.7903838949.

The spelling of 61531811 in words is "sixty-one million, five hundred thirty-one thousand, eight hundred eleven".