21993460 has 24 divisors (see below), whose sum is σ = 46345320. Its totient is φ = 8767104.

The previous prime is 21993437. The next prime is 21993467. The reversal of 21993460 is 6439912.

It can be written as a sum of positive squares in 4 ways, for example, as 1454436 + 20539024 = 1206^2 + 4532^2 .

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21993467) 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, 4606 + ... + 8074.

It is an arithmetic number, because the mean of its divisors is an integer number (1931055).

Almost surely, 2^21993460 is an apocalyptic number.

21993460 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21993460 is an abundant number, since it is smaller than the sum of its proper divisors (24351860).

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

21993460 is a wasteful number, since it uses less digits than its factorization.

21993460 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3795 (or 3793 counting only the distinct ones).

The product of its (nonzero) digits is 11664, while the sum is 34.

The square root of 21993460 is about 4689.7185416611. The cubic root of 21993460 is about 280.1761646513.

The spelling of 21993460 in words is "twenty-one million, nine hundred ninety-three thousand, four hundred sixty".