21970290 has 64 divisors (see below), whose sum is σ = 58288896. Its totient is φ = 5271552.

The previous prime is 21970271. The next prime is 21970297. The reversal of 21970290 is 9207912.

It is a Harshad number since it is a multiple of its sum of digits (30).

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 31 ways as a sum of consecutive naturals, for example, 10794 + ... + 12666.

It is an arithmetic number, because the mean of its divisors is an integer number (910764).

Almost surely, 2^21970290 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21970290, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (29144448).

21970290 is an abundant number, since it is smaller than the sum of its proper divisors (36318606).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21970290 is a wasteful number, since it uses less digits than its factorization.

21970290 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1923.

The product of its (nonzero) digits is 2268, while the sum is 30.

The square root of 21970290 is about 4687.2475932044. The cubic root of 21970290 is about 280.0777420184.

The spelling of 21970290 in words is "twenty-one million, nine hundred seventy thousand, two hundred ninety".