61981531 has 4 divisors (see below), whose sum is σ = 62023752. Its totient is φ = 61939312.

The previous prime is 61981511. The next prime is 61981537. The reversal of 61981531 is 13518916.

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 61981531 - 2⁹ = 61981019 is a prime.

It is a super-2 number, since 2×61981531² = 7683420370207922, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (61981537) 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, 18826 + ... + 21871.

It is an arithmetic number, because the mean of its divisors is an integer number (15505938).

Almost surely, 2^61981531 is an apocalyptic number.

61981531 is a deficient number, since it is larger than the sum of its proper divisors (42221).

61981531 is a wasteful number, since it uses less digits than its factorization.

61981531 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 42220.

The product of its digits is 6480, while the sum is 34.

The square root of 61981531 is about 7872.8350039868. The cubic root of 61981531 is about 395.7498569037.

The spelling of 61981531 in words is "sixty-one million, nine hundred eighty-one thousand, five hundred thirty-one".