21481964 has 24 divisors (see below), whose sum is σ = 43131648. Its totient is φ = 9170640.

The previous prime is 21481963. The next prime is 21482029. The reversal of 21481964 is 46918412.

It is a happy number.

It is a super-2 number, since 2×21481964² = 922949554594592, which contains 22 as substring.

It is a Smith number, since the sum of its digits (35) coincides with the sum of the digits of its prime factors.

It is not an unprimeable number, because it can be changed into a prime (21481963) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 6569 + ... + 9279.

It is an arithmetic number, because the mean of its divisors is an integer number (1797152).

Almost surely, 2^21481964 is an apocalyptic number.

It is an amenable number.

21481964 is an abundant number, since it is smaller than the sum of its proper divisors (21649684).

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

21481964 is a wasteful number, since it uses less digits than its factorization.

21481964 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3005 (or 3003 counting only the distinct ones).

The product of its digits is 13824, while the sum is 35.

The square root of 21481964 is about 4634.8639677988. The cubic root of 21481964 is about 277.9871118708.

The spelling of 21481964 in words is "twenty-one million, four hundred eighty-one thousand, nine hundred sixty-four".