21007481 has 8 divisors (see below), whose sum is σ = 23306400. Its totient is φ = 18773440.

The previous prime is 21007463. The next prime is 21007499. The reversal of 21007481 is 18470012.

It is an interprime number because it is at equal distance from previous prime (21007463) and next prime (21007499).

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

It is a cyclic number.

It is not a de Polignac number, because 21007481 - 2¹⁴ = 20991097 is a prime.

It is a super-2 number, since 2×21007481² = 882628515930722, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21007681) 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, 15536 + ... + 16833.

It is an arithmetic number, because the mean of its divisors is an integer number (2913300).

Almost surely, 2^21007481 is an apocalyptic number.

It is an amenable number.

21007481 is a deficient number, since it is larger than the sum of its proper divisors (2298919).

21007481 is a wasteful number, since it uses less digits than its factorization.

21007481 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 32439.

The product of its (nonzero) digits is 448, while the sum is 23.

The square root of 21007481 is about 4583.3918662929. The cubic root of 21007481 is about 275.9251748784.

Adding to 21007481 its reverse (18470012), we get a palindrome (39477493).

The spelling of 21007481 in words is "twenty-one million, seven thousand, four hundred eighty-one".