21100431 has 32 divisors (see below), whose sum is σ = 32820480. Its totient is φ = 11923200.

The previous prime is 21100423. The next prime is 21100441. The reversal of 21100431 is 13400112.

It is a happy number.

It is not a de Polignac number, because 21100431 - 2³ = 21100423 is a prime.

It is a super-2 number, since 2×21100431² = 890456376771522, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21100411) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 45541 + ... + 46001.

It is an arithmetic number, because the mean of its divisors is an integer number (1025640).

Almost surely, 2^21100431 is an apocalyptic number.

21100431 is a deficient number, since it is larger than the sum of its proper divisors (11720049).

21100431 is a wasteful number, since it uses less digits than its factorization.

21100431 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 567.

The product of its (nonzero) digits is 24, while the sum is 12.

The square root of 21100431 is about 4593.5205452899. The cubic root of 21100431 is about 276.3315302989.

Adding to 21100431 its reverse (13400112), we get a palindrome (34500543).

The spelling of 21100431 in words is "twenty-one million, one hundred thousand, four hundred thirty-one".