21001970 has 48 divisors (see below), whose sum is σ = 44040024. Its totient is φ = 7180800.

The previous prime is 21001969. The next prime is 21001979. The reversal of 21001970 is 7910012.

It can be written as a sum of positive squares in 4 ways, for example, as 19456921 + 1545049 = 4411^2 + 1243^2 .

It is not an unprimeable number, because it can be changed into a prime (21001979) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 20060 + ... + 21080.

Almost surely, 2^21001970 is an apocalyptic number.

21001970 is an abundant number, since it is smaller than the sum of its proper divisors (23038054).

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

21001970 is a wasteful number, since it uses less digits than its factorization.

21001970 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1067 (or 1056 counting only the distinct ones).

The product of its (nonzero) digits is 126, while the sum is 20.

The square root of 21001970 is about 4582.7906345370. The cubic root of 21001970 is about 275.9010444805.

Adding to 21001970 its reverse (7910012), we get a palindrome (28911982).

The spelling of 21001970 in words is "twenty-one million, one thousand, nine hundred seventy".