21820465 has 4 divisors (see below), whose sum is σ = 26184564. Its totient is φ = 17456368.

The previous prime is 21820459. The next prime is 21820481. The reversal of 21820465 is 56402812.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 6210064 + 15610401 = 2492^2 + 3951^2 .

It is a cyclic number.

It is not a de Polignac number, because 21820465 - 2³ = 21820457 is a prime.

It is a super-2 number, since 2×21820465² = 952265385632450, which contains 22 as substring.

It is a Duffinian number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2182042 + ... + 2182051.

It is an arithmetic number, because the mean of its divisors is an integer number (6546141).

Almost surely, 2^21820465 is an apocalyptic number.

It is an amenable number.

21820465 is a deficient number, since it is larger than the sum of its proper divisors (4364099).

21820465 is an equidigital number, since it uses as much as digits as its factorization.

21820465 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4364098.

The product of its (nonzero) digits is 3840, while the sum is 28.

The square root of 21820465 is about 4671.2380585879. The cubic root of 21820465 is about 279.4396318260.

The spelling of 21820465 in words is "twenty-one million, eight hundred twenty thousand, four hundred sixty-five".