21597380 has 24 divisors (see below), whose sum is σ = 51834048. Its totient is φ = 7404768.

The previous prime is 21597377. The next prime is 21597427. The reversal of 21597380 is 8379512.

It is a Harshad number since it is a multiple of its sum of digits (35).

It is a self number, because there is not a number n which added to its sum of digits gives 21597380.

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, 76994 + ... + 77273.

It is an arithmetic number, because the mean of its divisors is an integer number (2159752).

Almost surely, 2^21597380 is an apocalyptic number.

21597380 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21597380 is an abundant number, since it is smaller than the sum of its proper divisors (30236668).

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

21597380 is a wasteful number, since it uses less digits than its factorization.

21597380 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 154283 (or 154281 counting only the distinct ones).

The product of its (nonzero) digits is 15120, while the sum is 35.

The square root of 21597380 is about 4647.2981397797. The cubic root of 21597380 is about 278.4840694108.

The spelling of 21597380 in words is "twenty-one million, five hundred ninety-seven thousand, three hundred eighty".