21970145 has 4 divisors (see below), whose sum is σ = 26364180. Its totient is φ = 17576112.

The previous prime is 21970121. The next prime is 21970147. The reversal of 21970145 is 54107912.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 5841889 + 16128256 = 2417^2 + 4016^2 .

It is a cyclic number.

It is not a de Polignac number, because 21970145 - 2¹⁶ = 21904609 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21970147) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2197010 + ... + 2197019.

It is an arithmetic number, because the mean of its divisors is an integer number (6591045).

Almost surely, 2^21970145 is an apocalyptic number.

It is an amenable number.

21970145 is a deficient number, since it is larger than the sum of its proper divisors (4394035).

21970145 is an equidigital number, since it uses as much as digits as its factorization.

21970145 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4394034.

The product of its (nonzero) digits is 2520, while the sum is 29.

The square root of 21970145 is about 4687.2321256793. The cubic root of 21970145 is about 280.0771258626.

The spelling of 21970145 in words is "twenty-one million, nine hundred seventy thousand, one hundred forty-five".