21977943 has 24 divisors (see below), whose sum is σ = 32254848. Its totient is φ = 13302432.

The previous prime is 21977941. The next prime is 21977953. The reversal of 21977943 is 34977912.

It is not a de Polignac number, because 21977943 - 2¹ = 21977941 is a prime.

It is a super-2 number, since 2×21977943² = 966059957022498, which contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 21977895 and 21977904.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21977941) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 33646 + ... + 34292.

It is an arithmetic number, because the mean of its divisors is an integer number (1343952).

Almost surely, 2^21977943 is an apocalyptic number.

21977943 is a deficient number, since it is larger than the sum of its proper divisors (10276905).

21977943 is a wasteful number, since it uses less digits than its factorization.

21977943 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 743 (or 730 counting only the distinct ones).

The product of its digits is 95256, while the sum is 42.

The square root of 21977943 is about 4688.0638860835. The cubic root of 21977943 is about 280.1102584475.

The spelling of 21977943 in words is "twenty-one million, nine hundred seventy-seven thousand, nine hundred forty-three".