977990221 has 4 divisors (see below), whose sum is σ = 1053220252. Its totient is φ = 902760192.

The previous prime is 977990219. The next prime is 977990227. The reversal of 977990221 is 122099779.

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

It can be written as a sum of positive squares in 2 ways, for example, as 562401225 + 415588996 = 23715^2 + 20386^2 .

It is a cyclic number.

It is not a de Polignac number, because 977990221 - 2¹ = 977990219 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 (977990227) 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, 37614996 + ... + 37615021.

It is an arithmetic number, because the mean of its divisors is an integer number (263305063).

Almost surely, 2^977990221 is an apocalyptic number.

It is an amenable number.

977990221 is a deficient number, since it is larger than the sum of its proper divisors (75230031).

977990221 is a wasteful number, since it uses less digits than its factorization.

977990221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 75230030.

The product of its (nonzero) digits is 142884, while the sum is 46.

The square root of 977990221 is about 31272.8351928635. The cubic root of 977990221 is about 992.6089134264.

It can be divided in two parts, 9779 and 90221, that added together give a 5-th power (100000 = 10⁵).

The spelling of 977990221 in words is "nine hundred seventy-seven million, nine hundred ninety thousand, two hundred twenty-one".