97811781 has 4 divisors (see below), whose sum is σ = 130415712. Its totient is φ = 65207852.

The previous prime is 97811737. The next prime is 97811797. The reversal of 97811781 is 18711879.

It is a happy number.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 97811781 - 2⁹ = 97811269 is a prime.

It is a super-2 number, since 2×97811781² = 19134289004783922, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (97810781) 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, 16301961 + ... + 16301966.

It is an arithmetic number, because the mean of its divisors is an integer number (32603928).

Almost surely, 2^97811781 is an apocalyptic number.

It is an amenable number.

97811781 is a deficient number, since it is larger than the sum of its proper divisors (32603931).

97811781 is a wasteful number, since it uses less digits than its factorization.

97811781 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 32603930.

The product of its digits is 28224, while the sum is 42.

The square root of 97811781 is about 9889.9838725854. The cubic root of 97811781 is about 460.7482795970.

The spelling of 97811781 in words is "ninety-seven million, eight hundred eleven thousand, seven hundred eighty-one".