21121983 has 6 divisors (see below), whose sum is σ = 30509544. Its totient is φ = 14081316.

The previous prime is 21121979. The next prime is 21121999. The reversal of 21121983 is 38912112.

It is not a de Polignac number, because 21121983 - 2² = 21121979 is a prime.

It is a super-2 number, since 2×21121983² = 892276331704578, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21121913) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 1173435 + ... + 1173452.

It is an arithmetic number, because the mean of its divisors is an integer number (5084924).

Almost surely, 2^21121983 is an apocalyptic number.

21121983 is a deficient number, since it is larger than the sum of its proper divisors (9387561).

21121983 is a wasteful number, since it uses less digits than its factorization.

21121983 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2346893 (or 2346890 counting only the distinct ones).

The product of its digits is 864, while the sum is 27.

The square root of 21121983 is about 4595.8658596613. The cubic root of 21121983 is about 276.4255800467.

It can be divided in two parts, 2112 and 1983, that added together give a triangular number (4095 = T₉₀).

The spelling of 21121983 in words is "twenty-one million, one hundred twenty-one thousand, nine hundred eighty-three".