21970261 has 4 divisors (see below), whose sum is σ = 21995392. Its totient is φ = 21945132.

The previous prime is 21970229. The next prime is 21970271. The reversal of 21970261 is 16207912.

It is a happy number.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 21970261 - 2⁵ = 21970229 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21970271) 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, 11205 + ... + 13018.

It is an arithmetic number, because the mean of its divisors is an integer number (5498848).

Almost surely, 2^21970261 is an apocalyptic number.

It is an amenable number.

21970261 is a deficient number, since it is larger than the sum of its proper divisors (25131).

21970261 is an equidigital number, since it uses as much as digits as its factorization.

21970261 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 25130.

The product of its (nonzero) digits is 1512, while the sum is 28.

The square root of 21970261 is about 4687.2444997034. The cubic root of 21970261 is about 280.0776187874.

The spelling of 21970261 in words is "twenty-one million, nine hundred seventy thousand, two hundred sixty-one".