21917420 has 48 divisors (see below), whose sum is σ = 55702080. Its totient is φ = 7071744.

The previous prime is 21917419. The next prime is 21917429. The reversal of 21917420 is 2471912.

It is a self number, because there is not a number n which added to its sum of digits gives 21917420.

It is not an unprimeable number, because it can be changed into a prime (21917429) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 2225 + ... + 6984.

It is an arithmetic number, because the mean of its divisors is an integer number (1160460).

Almost surely, 2^21917420 is an apocalyptic number.

21917420 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21917420 is an abundant number, since it is smaller than the sum of its proper divisors (33784660).

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

21917420 is a wasteful number, since it uses less digits than its factorization.

21917420 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9242 (or 9240 counting only the distinct ones).

The product of its (nonzero) digits is 1008, while the sum is 26.

The square root of 21917420 is about 4681.6044258352. The cubic root of 21917420 is about 279.8528989228.

The spelling of 21917420 in words is "twenty-one million, nine hundred seventeen thousand, four hundred twenty".