21711431 has 16 divisors (see below), whose sum is σ = 26889984. Its totient is φ = 17103744.

The previous prime is 21711421. The next prime is 21711451. The reversal of 21711431 is 13411712.

It is a happy number.

It is a de Polignac number, because none of the positive numbers 2^k-21711431 is a prime.

It is a super-2 number, since 2×21711431² = 942772472135522, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21711421) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 2996 + ... + 7238.

It is an arithmetic number, because the mean of its divisors is an integer number (1680624).

Almost surely, 2^21711431 is an apocalyptic number.

21711431 is a deficient number, since it is larger than the sum of its proper divisors (5178553).

21711431 is a wasteful number, since it uses less digits than its factorization.

21711431 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4310.

The product of its digits is 168, while the sum is 20.

The square root of 21711431 is about 4659.5526609322. The cubic root of 21711431 is about 278.9734133614.

The spelling of 21711431 in words is "twenty-one million, seven hundred eleven thousand, four hundred thirty-one".