21490775 has 12 divisors (see below), whose sum is σ = 26972232. Its totient is φ = 16983840.

The previous prime is 21490759. The next prime is 21490783. The reversal of 21490775 is 57709412.

It is not a de Polignac number, because 21490775 - 2⁴ = 21490759 is a prime.

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 3104 + ... + 7253.

It is an arithmetic number, because the mean of its divisors is an integer number (2247686).

Almost surely, 2^21490775 is an apocalyptic number.

21490775 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

21490775 is a deficient number, since it is larger than the sum of its proper divisors (5481457).

21490775 is a wasteful number, since it uses less digits than its factorization.

21490775 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10450 (or 10445 counting only the distinct ones).

The product of its (nonzero) digits is 17640, while the sum is 35.

The square root of 21490775 is about 4635.8143836871. The cubic root of 21490775 is about 278.0251128911.

The spelling of 21490775 in words is "twenty-one million, four hundred ninety thousand, seven hundred seventy-five".