21277961 has 4 divisors (see below), whose sum is σ = 21445632. Its totient is φ = 21110292.

The previous prime is 21277933. The next prime is 21277969. The reversal of 21277961 is 16977212.

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-21277961 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21277969) 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, 83645 + ... + 83898.

It is an arithmetic number, because the mean of its divisors is an integer number (5361408).

Almost surely, 2^21277961 is an apocalyptic number.

It is an amenable number.

21277961 is a deficient number, since it is larger than the sum of its proper divisors (167671).

21277961 is a wasteful number, since it uses less digits than its factorization.

21277961 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 167670.

The product of its digits is 10584, while the sum is 35.

The square root of 21277961 is about 4612.8040279205. The cubic root of 21277961 is about 277.1043453843.

The spelling of 21277961 in words is "twenty-one million, two hundred seventy-seven thousand, nine hundred sixty-one".