21671757 has 12 divisors (see below), whose sum is σ = 31493280. Its totient is φ = 14360328.

The previous prime is 21671743. The next prime is 21671791. The reversal of 21671757 is 75717612.

It is not a de Polignac number, because 21671757 - 2⁸ = 21671501 is a prime.

It is a hoax number, since the sum of its digits (36) coincides with the sum of the digits of its distinct prime factors.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21671737) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 5707 + ... + 8712.

It is an arithmetic number, because the mean of its divisors is an integer number (2624440).

Almost surely, 2^21671757 is an apocalyptic number.

It is an amenable number.

21671757 is a deficient number, since it is larger than the sum of its proper divisors (9821523).

21671757 is a wasteful number, since it uses less digits than its factorization.

21671757 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 14592 (or 14589 counting only the distinct ones).

The product of its digits is 20580, while the sum is 36.

The square root of 21671757 is about 4655.2934386567. The cubic root of 21671757 is about 278.8033840392.

The spelling of 21671757 in words is "twenty-one million, six hundred seventy-one thousand, seven hundred fifty-seven".