21989770 has 32 divisors (see below), whose sum is σ = 44193600. Its totient is φ = 7808640.

The previous prime is 21989761. The next prime is 21989777. The reversal of 21989770 is 7798912.

It is a happy number.

It is a Harshad number since it is a multiple of its sum of digits (43).

It is not an unprimeable number, because it can be changed into a prime (21989777) 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, 2406 + ... + 7054.

It is an arithmetic number, because the mean of its divisors is an integer number (1381050).

Almost surely, 2^21989770 is an apocalyptic number.

21989770 is an abundant number, since it is smaller than the sum of its proper divisors (22203830).

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

21989770 is a wasteful number, since it uses less digits than its factorization.

21989770 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4710.

The product of its (nonzero) digits is 63504, while the sum is 43.

The square root of 21989770 is about 4689.3251113566. The cubic root of 21989770 is about 280.1604947223.

The spelling of 21989770 in words is "twenty-one million, nine hundred eighty-nine thousand, seven hundred seventy".