21709494 has 24 divisors (see below), whose sum is σ = 47151000. Its totient is φ = 7219008.

The previous prime is 21709477. The next prime is 21709511. The reversal of 21709494 is 49490712.

It is an interprime number because it is at equal distance from previous prime (21709477) and next prime (21709511).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 7774 + ... + 10190.

It is an arithmetic number, because the mean of its divisors is an integer number (1964625).

Almost surely, 2^21709494 is an apocalyptic number.

21709494 is an abundant number, since it is smaller than the sum of its proper divisors (25441506).

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

21709494 is a wasteful number, since it uses less digits than its factorization.

21709494 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2924 (or 2921 counting only the distinct ones).

The product of its (nonzero) digits is 18144, while the sum is 36.

The square root of 21709494 is about 4659.3448037251. The cubic root of 21709494 is about 278.9651168474.

It can be divided in two parts, 2170 and 9494, that added together give a square (11664 = 108²).

The spelling of 21709494 in words is "twenty-one million, seven hundred nine thousand, four hundred ninety-four".