21970291 has 16 divisors (see below), whose sum is σ = 26256384. Its totient is φ = 17990784.

The previous prime is 21970271. The next prime is 21970297. The reversal of 21970291 is 19207912.

It is not a de Polignac number, because 21970291 - 2¹³ = 21962099 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21970297) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 13371 + ... + 14923.

It is an arithmetic number, because the mean of its divisors is an integer number (1641024).

Almost surely, 2^21970291 is an apocalyptic number.

21970291 is a deficient number, since it is larger than the sum of its proper divisors (4286093).

21970291 is a wasteful number, since it uses less digits than its factorization.

21970291 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1650.

The product of its (nonzero) digits is 2268, while the sum is 31.

The square root of 21970291 is about 4687.2476998768. The cubic root of 21970291 is about 280.0777462677.

The spelling of 21970291 in words is "twenty-one million, nine hundred seventy thousand, two hundred ninety-one".