21245091 has 8 divisors (see below), whose sum is σ = 32373504. Its totient is φ = 12140040.

The previous prime is 21245057. The next prime is 21245099. The reversal of 21245091 is 19054212.

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

It is not a de Polignac number, because 21245091 - 2⁶ = 21245027 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21245099) 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, 505815 + ... + 505856.

It is an arithmetic number, because the mean of its divisors is an integer number (4046688).

Almost surely, 2^21245091 is an apocalyptic number.

21245091 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

21245091 is a deficient number, since it is larger than the sum of its proper divisors (11128413).

21245091 is a wasteful number, since it uses less digits than its factorization.

21245091 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1011681.

The product of its (nonzero) digits is 720, while the sum is 24.

The square root of 21245091 is about 4609.2397420833. The cubic root of 21245091 is about 276.9615824246.

The spelling of 21245091 in words is "twenty-one million, two hundred forty-five thousand, ninety-one".