21439475 has 6 divisors (see below), whose sum is σ = 26584980. Its totient is φ = 17151560.

The previous prime is 21439471. The next prime is 21439489. The reversal of 21439475 is 57493412.

It is not a de Polignac number, because 21439475 - 2² = 21439471 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21439471) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 428765 + ... + 428814.

It is an arithmetic number, because the mean of its divisors is an integer number (4430830).

Almost surely, 2^21439475 is an apocalyptic number.

21439475 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

21439475 is a deficient number, since it is larger than the sum of its proper divisors (5145505).

21439475 is an equidigital number, since it uses as much as digits as its factorization.

21439475 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 857589 (or 857584 counting only the distinct ones).

The product of its digits is 30240, while the sum is 35.

The square root of 21439475 is about 4630.2780694036. The cubic root of 21439475 is about 277.8037147633.

The spelling of 21439475 in words is "twenty-one million, four hundred thirty-nine thousand, four hundred seventy-five".