21345775 has 12 divisors (see below), whose sum is σ = 28875384. Its totient is φ = 15524000.

The previous prime is 21345767. The next prime is 21345809. The reversal of 21345775 is 57754312.

It is not a de Polignac number, because 21345775 - 2³ = 21345767 is a prime.

It is a super-2 number, since 2×21345775² = 911284220701250, which contains 22 as substring.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21345775.

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, 38536 + ... + 39085.

It is an arithmetic number, because the mean of its divisors is an integer number (2406282).

Almost surely, 2^21345775 is an apocalyptic number.

21345775 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

21345775 is a deficient number, since it is larger than the sum of its proper divisors (7529609).

21345775 is a wasteful number, since it uses less digits than its factorization.

21345775 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 77642 (or 77637 counting only the distinct ones).

The product of its digits is 29400, while the sum is 34.

The square root of 21345775 is about 4620.1488071273. The cubic root of 21345775 is about 277.3984153239.

The spelling of 21345775 in words is "twenty-one million, three hundred forty-five thousand, seven hundred seventy-five".