21590023 has 16 divisors (see below), whose sum is σ = 27973120. Its totient is φ = 16181856.

The previous prime is 21590021. The next prime is 21590039. The reversal of 21590023 is 32009512.

It is a cyclic number.

It is not a de Polignac number, because 21590023 - 2¹ = 21590021 is a prime.

It is a super-2 number, since 2×21590023² = 932258186281058, which contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 21589976 and 21590003.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21590021) 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, 4515 + ... + 7972.

It is an arithmetic number, because the mean of its divisors is an integer number (1748320).

Almost surely, 2^21590023 is an apocalyptic number.

21590023 is a deficient number, since it is larger than the sum of its proper divisors (6383097).

21590023 is a wasteful number, since it uses less digits than its factorization.

21590023 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 12526.

The product of its (nonzero) digits is 540, while the sum is 22.

The square root of 21590023 is about 4646.5065371739. The cubic root of 21590023 is about 278.4524445875.

Adding to 21590023 its reverse (32009512), we get a palindrome (53599535).

The spelling of 21590023 in words is "twenty-one million, five hundred ninety thousand, twenty-three".