21408958 has 4 divisors (see below), whose sum is σ = 32113440. Its totient is φ = 10704478.

The previous prime is 21408949. The next prime is 21408971. The reversal of 21408958 is 85980412.

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

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5352238 + ... + 5352241.

It is an arithmetic number, because the mean of its divisors is an integer number (8028360).

Almost surely, 2^21408958 is an apocalyptic number.

21408958 is a deficient number, since it is larger than the sum of its proper divisors (10704482).

21408958 is a wasteful number, since it uses less digits than its factorization.

21408958 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10704481.

The product of its (nonzero) digits is 23040, while the sum is 37.

The square root of 21408958 is about 4626.9815214673. The cubic root of 21408958 is about 277.6718433508.

It can be divided in two parts, 21408 and 958, that added together give a triangular number (22366 = T₂₁₁).

The spelling of 21408958 in words is "twenty-one million, four hundred eight thousand, nine hundred fifty-eight".