97777721 has 4 divisors (see below), whose sum is σ = 99154944. Its totient is φ = 96400500.

The previous prime is 97777711. The next prime is 97777741. The reversal of 97777721 is 12777779.

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 a de Polignac number, because none of the positive numbers 2^k-97777721 is a prime.

It is a Duffinian number.

It is a nialpdrome in base 10.

It is not an unprimeable number, because it can be changed into a prime (97777711) 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, 688505 + ... + 688646.

It is an arithmetic number, because the mean of its divisors is an integer number (24788736).

Almost surely, 2^97777721 is an apocalyptic number.

It is an amenable number.

97777721 is a deficient number, since it is larger than the sum of its proper divisors (1377223).

97777721 is a wasteful number, since it uses less digits than its factorization.

97777721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1377222.

The product of its digits is 302526, while the sum is 47.

The square root of 97777721 is about 9888.2617784927. The cubic root of 97777721 is about 460.6947928283.

The spelling of 97777721 in words is "ninety-seven million, seven hundred seventy-seven thousand, seven hundred twenty-one".