21473240 has 32 divisors (see below), whose sum is σ = 49001760. Its totient is φ = 8467200.

The previous prime is 21473239. The next prime is 21473267. The reversal of 21473240 is 4237412.

It is a super-2 number, since 2×21473240² = 922200072195200, which contains 22 as substring.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 941 + ... + 6620.

It is an arithmetic number, because the mean of its divisors is an integer number (1531305).

Almost surely, 2^21473240 is an apocalyptic number.

21473240 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21473240 is an abundant number, since it is smaller than the sum of its proper divisors (27528520).

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

21473240 is a wasteful number, since it uses less digits than its factorization.

21473240 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7643 (or 7639 counting only the distinct ones).

The product of its (nonzero) digits is 1344, while the sum is 23.

The square root of 21473240 is about 4633.9227442848. The cubic root of 21473240 is about 277.9494758345.

The spelling of 21473240 in words is "twenty-one million, four hundred seventy-three thousand, two hundred forty".