21465390 has 32 divisors (see below), whose sum is σ = 54548640. Its totient is φ = 5387264.

The previous prime is 21465349. The next prime is 21465391. The reversal of 21465390 is 9356412.

21465390 = 528² + 529² + ... + 595².

It is a Harshad number since it is a multiple of its sum of digits (30).

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21465391) 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, 20535 + ... + 21554.

It is an arithmetic number, because the mean of its divisors is an integer number (1704645).

Almost surely, 2^21465390 is an apocalyptic number.

21465390 is an abundant number, since it is smaller than the sum of its proper divisors (33083250).

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

21465390 is a wasteful number, since it uses less digits than its factorization.

21465390 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 42116.

The product of its (nonzero) digits is 6480, while the sum is 30.

The square root of 21465390 is about 4633.0756523070. The cubic root of 21465390 is about 277.9156015904.

The spelling of 21465390 in words is "twenty-one million, four hundred sixty-five thousand, three hundred ninety".