21951973 has 16 divisors (see below), whose sum is σ = 23974720. Its totient is φ = 20030976.

The previous prime is 21951971. The next prime is 21951977. The reversal of 21951973 is 37915912.

It is a cyclic number.

It is not a de Polignac number, because 21951973 - 2¹ = 21951971 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21951971) 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, 79111 + ... + 79387.

It is an arithmetic number, because the mean of its divisors is an integer number (1498420).

Almost surely, 2^21951973 is an apocalyptic number.

It is an amenable number.

21951973 is a deficient number, since it is larger than the sum of its proper divisors (2022747).

21951973 is a wasteful number, since it uses less digits than its factorization.

21951973 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 436.

The product of its digits is 17010, while the sum is 37.

The square root of 21951973 is about 4685.2932672353. The cubic root of 21951973 is about 279.9998852040. Note that the first 3 decimals are identical.

The spelling of 21951973 in words is "twenty-one million, nine hundred fifty-one thousand, nine hundred seventy-three".