21213942 has 32 divisors (see below), whose sum is σ = 43535232. Its totient is φ = 6889344.

The previous prime is 21213931. The next prime is 21213947. The reversal of 21213942 is 24931212.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21213947) 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, 45193 + ... + 45659.

It is an arithmetic number, because the mean of its divisors is an integer number (1360476).

Almost surely, 2^21213942 is an apocalyptic number.

21213942 is an abundant number, since it is smaller than the sum of its proper divisors (22321290).

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

21213942 is a wasteful number, since it uses less digits than its factorization.

21213942 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 652.

The product of its digits is 864, while the sum is 24.

The square root of 21213942 is about 4605.8595289045. The cubic root of 21213942 is about 276.8261582611.

It can be divided in two parts, 21213 and 942, that added together give a triangular number (22155 = T₂₁₀).

The spelling of 21213942 in words is "twenty-one million, two hundred thirteen thousand, nine hundred forty-two".