21297970 has 8 divisors (see below), whose sum is σ = 38336364. Its totient is φ = 8519184.

The previous prime is 21297953. The next prime is 21297973. The reversal of 21297970 is 7979212.

It can be written as a sum of positive squares in 2 ways, for example, as 20912329 + 385641 = 4573^2 + 621^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a super-2 number, since 2×21297970² = 907207052241800, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (21297973) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1064889 + ... + 1064908.

Almost surely, 2^21297970 is an apocalyptic number.

21297970 is a deficient number, since it is larger than the sum of its proper divisors (17038394).

21297970 is a wasteful number, since it uses less digits than its factorization.

21297970 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2129804.

The product of its (nonzero) digits is 15876, while the sum is 37.

The square root of 21297970 is about 4614.9723726150. The cubic root of 21297970 is about 277.1911776984.

It can be divided in two parts, 212979 and 70, that multiplied together give a triangular number (14908530 = T₅₄₆₀).

The spelling of 21297970 in words is "twenty-one million, two hundred ninety-seven thousand, nine hundred seventy".