21432690 has 24 divisors (see below), whose sum is σ = 55725228. Its totient is φ = 5715360.

The previous prime is 21432679. The next prime is 21432701. The reversal of 21432690 is 9623412.

It is an interprime number because it is at equal distance from previous prime (21432679) and next prime (21432701).

It can be written as a sum of positive squares in 2 ways, for example, as 20493729 + 938961 = 4527^2 + 969^2 .

It is a super-2 number, since 2×21432690² = 918720401272200, which contains 22 as substring.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 118981 + ... + 119160.

Almost surely, 2^21432690 is an apocalyptic number.

21432690 is an abundant number, since it is smaller than the sum of its proper divisors (34292538).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21432690 is a wasteful number, since it uses less digits than its factorization.

21432690 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 238154 (or 238151 counting only the distinct ones).

The product of its (nonzero) digits is 2592, while the sum is 27.

The square root of 21432690 is about 4629.5453340474. The cubic root of 21432690 is about 277.7744059443.

It can be divided in two parts, 21432 and 690, that added together give a palindrome (22122).

The spelling of 21432690 in words is "twenty-one million, four hundred thirty-two thousand, six hundred ninety".