21277161 has 10 divisors (see below), whose sum is σ = 31784522. Its totient is φ = 14184720.

The previous prime is 21277159. The next prime is 21277163. The reversal of 21277161 is 16177212.

It is an interprime number because it is at equal distance from previous prime (21277159) and next prime (21277163).

It can be written as a sum of positive squares in only one way, i.e., 20985561 + 291600 = 4581^2 + 540^2 .

It is not a de Polignac number, because 21277161 - 2¹ = 21277159 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21277163) by changing a digit.

It is a polite number, since it can be written in 9 ways as a sum of consecutive naturals, for example, 131260 + ... + 131421.

Almost surely, 2^21277161 is an apocalyptic number.

It is an amenable number.

21277161 is a deficient number, since it is larger than the sum of its proper divisors (10507361).

21277161 is an equidigital number, since it uses as much as digits as its factorization.

21277161 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 262693 (or 262684 counting only the distinct ones).

The product of its digits is 1176, while the sum is 27.

The square root of 21277161 is about 4612.7173119540. The cubic root of 21277161 is about 277.1008725225.

The spelling of 21277161 in words is "twenty-one million, two hundred seventy-seven thousand, one hundred sixty-one".