21431029 has 8 divisors (see below), whose sum is σ = 22770360. Its totient is φ = 20131776.

The previous prime is 21431023. The next prime is 21431057. The reversal of 21431029 is 92013412.

It can be written as a sum of positive squares in 4 ways, for example, as 6260004 + 15171025 = 2502^2 + 3895^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21431029 - 2¹³ = 21422837 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21431023) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 8914 + ... + 11059.

It is an arithmetic number, because the mean of its divisors is an integer number (2846295).

Almost surely, 2^21431029 is an apocalyptic number.

21431029 is a gapful number since it is divisible by the number (29) formed by its first and last digit.

It is an amenable number.

21431029 is a deficient number, since it is larger than the sum of its proper divisors (1339331).

21431029 is a wasteful number, since it uses less digits than its factorization.

21431029 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 20039.

The product of its (nonzero) digits is 432, while the sum is 22.

The square root of 21431029 is about 4629.3659393053. The cubic root of 21431029 is about 277.7672300647.

The spelling of 21431029 in words is "twenty-one million, four hundred thirty-one thousand, twenty-nine".