21171377 has 4 divisors (see below), whose sum is σ = 22285680. Its totient is φ = 20057076.

The previous prime is 21171373. The next prime is 21171379. The reversal of 21171377 is 77317112.

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 not a de Polignac number, because 21171377 - 2² = 21171373 is a prime.

It is a super-2 number, since 2×21171377² = 896454408152258, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21171373) 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, 557123 + ... + 557160.

It is an arithmetic number, because the mean of its divisors is an integer number (5571420).

Almost surely, 2^21171377 is an apocalyptic number.

It is an amenable number.

21171377 is a deficient number, since it is larger than the sum of its proper divisors (1114303).

21171377 is a wasteful number, since it uses less digits than its factorization.

21171377 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1114302.

The product of its digits is 2058, while the sum is 29.

The square root of 21171377 is about 4601.2364642561. The cubic root of 21171377 is about 276.6408870997.

Adding to 21171377 its reverse (77317112), we get a palindrome (98488489).

The spelling of 21171377 in words is "twenty-one million, one hundred seventy-one thousand, three hundred seventy-seven".