21161977 has 8 divisors (see below), whose sum is σ = 21781760. Its totient is φ = 20548080.

The previous prime is 21161971. The next prime is 21161981. The reversal of 21161977 is 77916112.

21161977 is nontrivially palindromic in base 5.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21161977 - 2¹⁵ = 21129209 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21161971) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 6424 + ... + 9142.

It is an arithmetic number, because the mean of its divisors is an integer number (2722720).

Almost surely, 2^21161977 is an apocalyptic number.

It is an amenable number.

21161977 is a deficient number, since it is larger than the sum of its proper divisors (619783).

21161977 is a wasteful number, since it uses less digits than its factorization.

21161977 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2943.

The product of its digits is 5292, while the sum is 34.

The square root of 21161977 is about 4600.2148862852. The cubic root of 21161977 is about 276.5999385856.

The spelling of 21161977 in words is "twenty-one million, one hundred sixty-one thousand, nine hundred seventy-seven".